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  • 2010-2014  (49)
  • 1995-1999  (20)
  • 1980-1984  (12)
  • 1
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    High-pressure I2/c - P21/c phase transformation in SrAl2Si2O8 feldspar (2011)
    In:  American Mineralogist
    Details
    Publication Date: 2020-02-12
    Keywords: 550 - Earth sciences
    Type: info:eu-repo/semantics/article
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  • 2
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    High-pressure behaviour of SrAl2Si2O8 feldspar (2010)
    In:  Acta Mineralogica-Petrographica, Abstract Series ; 6
    Details
    Publication Date: 2020-02-12
    Keywords: 550 - Earth sciences
    Type: info:eu-repo/semantics/conferenceObject
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  • 3
    Electronic Resource
    Electronic Resource
    Crystal structures of Ca-rich clinopyroxenes on the CaMgSi2O6-Mg2Si2O6 join (1982)
    Springer
    Mineralogy and petrology 29 (1982), S. 223-240 
    Details
    ISSN: 1438-1168
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Description / Table of Contents: Zusammenfassung Es wurden die strukturellen Änderungen von Klinopyroxenen der Zusammensetzungen Di100, Di90En10 und Di80En20, die durch den Mg-Ersatz für Ca verursacht werden, untersucht. Es zeigt sich, daß mit steigendem Mg-Gehalt ein kleiner Teil der Atome der M2-Position zu einer neuen M2′-Position wechselt; diese wird ausschließlich durch Mg besetzt. Der größte in dieser Arbeit gefundene Übergang von M2 nach M2′ beträgt ca. 7%. Die stärksten Parallelen zur Geometrie um M2′ werden im Pyroxen ZnSiO3 (C2/c) gefunden. Die Besetzung dieser neuen Position verursacht bedeutende Änderungen im Tetraederverband, da die M2′-Atome nicht an O3 gebunden sind. Die Pyroxenstrukturen mit den intermediären Zusammensetzungen Di90En10 und Di80En20 können als Überlagerung zweier Modelle betrachtet werden: Diopsid und ZnSiO3-Pyroxen (C2/c).
    Notes: Summary The structural changes occurring in the clinopyroxenes with composition Di100, Di90En10 and Di80En20, due to the Ca-Mg substitution in the M2 site, have been studied. Evidence is given that with increasing Mg content a small percentage of the atoms converts from the M2 position to a new M2′ position which is solely occupied by Mg. The maximum conversion of M2 to M2′ found in this study is 7%. The closest parallel to the M2′ geometry is found in the ZnSiO3 pyroxene (C2/c). The presence of this new site causes significant changes in the tetrahedral configuration, because the M2′ atoms are not bonded to 03. The intermediate compositions, Di90En10 and Di80En20, may be thought of as the coexistence of two structural models: diopside and ZnSiO3 pyroxene (C2/c).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01091794
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  • 4
    Electronic Resource
    Electronic Resource
    Al-Si ordering in Sr-feldspar SrAl2Si2O8: IR, TEM and single-crystal XRD evidences (1995)
    Springer
    Physics and chemistry of minerals 22 (1995), S. 343-350 
    Details
    ISSN: 1432-2021
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Abstract Al-Si ordering in Sr-feldspar has been followed by isothermal annealing, starting from a disordered metastable configuration. Ordering could not be followed by changes in the spontaneous strain as cell parameters did not show significant changes with thermal treatment from 0.016 h to 452 h at T=1350° C, while, on the contrary, significant changes in IR spectra are observed. A single crystal obtained from melt (Q od≈ 0) has been progressively heated up to 678 h at T=1350° C and the relevant structural refinements enabled to monitor changes in degree of Al-Si order up to Qod = 0.86. In isothermal treatment for Sr-feldspar it is observed a significantly lower Q od than in anorthite after the same annealing time. TEM observation has shown in Sr-feldspar, also for shortest annealing, ‘b’ type reflections, while in anorthite, in the same conditions, ‘e’ type reflections have been observed (Carpenter 1991a). In the first stages of ordering ‘b’ APDs sized ≈ 100 Å (at T=1350° C, 0.33 h) have been observed in Sr-feldspar; APD coarsening occurs with an activation energy of 120±7 kcal mol-1, not significantly different from anorthite. The ordering process seems to be a slower process in Sr-feldspar than in anorthite, even though data from longer annealing suggest that the Q od close to the equilibrium is the same in Sr and Ca-feldspar (Q od = 0.86 at T=1350° C).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00213330
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  • 5
    Electronic Resource
    Electronic Resource
    Erratum (1982)
    Springer
    Mineralogy and petrology 30 (1982), S. 77-77 
    Details
    ISSN: 1438-1168
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01082428
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  • 6
    Electronic Resource
    Electronic Resource
    High pressure behaviour of lead feldspar (PbAl2Si2O8) (1999)
    Springer
    Physics and chemistry of minerals 26 (1999), S. 367-374 
    Details
    ISSN: 1432-2021
    Keywords: Key words Lead feldspar ; in situ HP powder diffraction ; Synchrotron radiation ; Bulk modulus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Abstract  An in situ high pressure powder diffraction study, using high-brilliance synchrotron radiation, on lead feldspar (PbAl2Si2O8) was performed. Two samples, with Q od=0.68 and 0.76, were loaded in a diamond anvil cell and were compressed up to 11 GPa. Up to P=7.1 GPa the only phase present is lead feldspar. In the range 7.1–9.4 GPa sudden changes in the position of the reflections suggest the transformation of lead feldspar to a new phase (probably feldspar-like). The absence of split that would be compatible with triclinic symmetry rules out the monoclinic-triclinic transition, that was reported for the structurally similar strontium feldspar. At P〉9.4 GPa some new extra reflections not indexable in the feldspar cell are present as well. During decompression the lead feldspar was the only phase present at P〈6 GPa. Peak enlargement was observed with pressure, probably preliminary to amorphization. However almost complete amorphization was observed only after fortuitous shock compression at ∼18 GPa; the crystallinity was recovered at room pressure after decompression. The bulk modulus for lead feldspar was K=71.0(9) and 67.6(1.2) GPa for the two samples, in the range reported for feldspars. The cell parameters show a compression pattern which is similar to that observed in anorthite, with Δa/a 0〉Δc/c 0〉Δb/b 0; comparison with the high temperature behaviour shows that for lead feldspar the strain tensor with pressure is more isotropic and the deformation along a is less prominent. A turnover in the behaviour of the β angle with pressure suggests a change in the compression behaviour at P∼2 GPa. Rietveld refinement of the Pb coordinates was performed in a series of spectra with pressure ranging from 0.6 to 6.5 GPa. The combined analysis of cell parameters and Pb coordinates with pressure showed that the compression of the structure is mainly achieved by an approach of Pb atoms along a *.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002690050196
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  • 7
    Electronic Resource
    Electronic Resource
    Candida albicans phosphatidylinositol synthase has common features with both Saccharomyces cerevisiae and mammalian phosphatidylinositol synthases (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 12 (1996), S. 449-456 
    Details
    ISSN: 0749-503X
    Keywords: inositol ; phosphatidylinositol synthase ; Candida albicans ; Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Phosphatidylinositol (PI) synthase (cytidine 5′-diphospho (CDP)-1,2-diacyl-sn-glycerol:myo-inositol 3phosphatidyltransferase, EC 2.7.8.11) was isolated from the microsomal cell fraction of Candida albicans. The Triton X-100 extracted enzyme was enriched 140-fold by affinity chromatography on CDP-diacylglycerol-Sepharose. The enzyme had a pH optimum at 9·5 in glycine/NaOH buffer. It had an absolute requirement for Mg2+ or Mn2+ and was inhibited by Ca2+ and Zn2+. Maximal activity was at 0·2-0·6 mm-CDP-diacylglycerol, higher concentrations inhibited the enzyme. With 2′-deoxy-CDP-diacylglycerol as the lipid substrate, optimal activity was at 0·7 mm. The Km for myo-inositol was determined to be 0·55 mm. The optimal temperature for the PI synthase reaction was 55°C. The C. albicans PI synthase shows differences to the Saccharomyces cerevisiae enzyme, such as activation by bivalent cations, inhibition by nucleotides, temperature optimum and activation energy, but also to the human PI synthase in preference for the lipid substrates, inhibition by nucleoside monophosphates and stabilization by Mn2+ and phospholipids.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 8
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    Multiple Sclerosis in the Mount Etna Region: Possible Role of Volcanogenic Trace Elements (2014)
    Public Library of Science
    Details
    Publication Date: 2017-04-04
    Description: Background: Trace elements have been hypothesised to be involved in the pathogenesis of Multiple Sclerosis and volcanic degassing is the major natural sources of trace elements. Both incidence of Multiple Sclerosis in Catania and volcanic activity of Mount Etna have been significantly increased during the last 30 years. Due to prevailing trade winds direction, volcanic gases from Etna summit craters are mostly blown towards the eastern and southern sectors of the volcano. Objective: To evaluate the possible association between Multiple Sclerosis and exposure to volcanogenic trace elements. Methods: We evaluated prevalence and incidence of Multiple Sclerosis in four communities (47,234 inhabitants) located in the eastern flank and in two communities (52,210 inhabitants) located in the western flank of Mount Etna, respectively the most and least exposed area to crater gas emissions. Results: A higher prevalence was found in the population of the eastern flank compared to the population of the western one (137.6/100,000 versus 94.3/100,000; p-value 0.04). We found a borderline significantly higher incidence risk during the incidence study period (1980–2009) in the population of the eastern flank 4.6/100,000 (95% CI 3.1–5.9), compared with the western population 3.2/100,000 (95% CI 2.4–4.2) with a RR of 1.41 (95% CI 0.97–2.05; p-value 0.06). Incidence risks have increased over the time in both populations reaching a peak of 6.4/100,000 in the eastern flank and of 4.4/100.000 in the western flank during 2000–2009. Conclusion: We found a higher prevalence and incidence of Multiple Sclerosis among populations living in the eastern flank of Mount Etna. According to our data a possible role of TE cannot be ruled out as possible co-factor in the MS pathogenesis. However larger epidemiological study are needed to confirm this hypothesis.
    Description: Published
    Description: e74259
    Description: 6A. Monitoraggio ambientale, sicurezza e territorio
    Description: JCR Journal
    Description: open
    Keywords: Mt. Etna volcano ; Multiple Sclerosis ; trace elements ; volcanic activity ; 05. General::05.08. Risk::05.08.01. Environmental risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 9
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    Ab InitioTheoretical Description of the Interrelation between Magnetocrystalline Anisotropy and Atomic Short-Range Order (1999)
    American Physical Society
    Details
    Publication Date: 1999-06-28
    Print ISSN: 0031-9007
    Electronic ISSN: 1079-7114
    Topics: Physics
    Published by American Physical Society
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  • 10
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    Incommensurate and Commensurate Antiferromagnetic Spin Fluctuations in Cr and Cr Alloys fromAb InitioDynamical Spin Susceptibility Calculations (1999)
    American Physical Society
    Details
    Publication Date: 1999-04-19
    Print ISSN: 0031-9007
    Electronic ISSN: 1079-7114
    Topics: Physics
    Published by American Physical Society
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