206 research outputs found
Iron sulphides at the epithermal gold-copper deposit of Palai-Islica (Almería, SE of Spain)
El artículo original ha sido publicado por la Mineralogical Society disponible en:
http://www.minersoc.org/pages/e_journals/minmag.htmlAu-Cu mineralisation at Palai-Islica occurs as disseminations in massive silicification and, more abundantly, in sulphide-bearing quartz veins. The major ore minerals in the deposit are pyrite ± chalcopyrite, sphalerite and galena and there are a great variety of accessory minerals, including Au-Ag alloys and native gold. Pyrite, the most abundant sulphide, is closely associated with gold. Seven different types of pyrite have been distinguished with a variable concentration of different trace elements. Among them only free of trace elements (type IV) is related to Au-Ag alloys. Pyrites associated with these Au-Ag alloys have a cubic and pentagonal dodecahedral habits whereas those with only the pentagonal dodecahedral habit are from barren zones. In addition, there is no significant invisible gold in pyrite, but there is relatively high Ag in collomorphic pyrite (up to 0.20 wt%) or type III pyrite (up to 1.47 wt%). As is the most abundant trace element in pyrite (up to 6.11 wt%), present as a metastable solid solution or as a non-stoichiometric element. Some kind of marcasite related with gold levels also have considerable amounts of trace elements (As, up to 1.15 wt%, Sb up to 0.40 wt%)Departamento de Mineralogía y Petrología.
Grupo de Investigación de la Junta de Andalucía RNM-0131.
Proyectos PB-97-1211 y BTE2001-330
Solar System Processes Underlying Planetary Formation, Geodynamics, and the Georeactor
Only three processes, operant during the formation of the Solar System, are
responsible for the diversity of matter in the Solar System and are directly
responsible for planetary internal-structures, including planetocentric nuclear
fission reactors, and for dynamical processes, including and especially,
geodynamics. These processes are: (i) Low-pressure, low-temperature
condensation from solar matter in the remote reaches of the Solar System or in
the interstellar medium; (ii) High-pressure, high-temperature condensation from
solar matter associated with planetary-formation by raining out from the
interiors of giant-gaseous protoplanets, and; (iii) Stripping of the primordial
volatile components from the inner portion of the Solar System by super-intense
solar wind associated with T-Tauri phase mass-ejections, presumably during the
thermonuclear ignition of the Sun. As described herein, these processes lead
logically, in a causally related manner, to a coherent vision of planetary
formation with profound implications including, but not limited to, (a) Earth
formation as a giant gaseous Jupiter-like planet with vast amounts of stored
energy of protoplanetary compression in its rock-plus-alloy kernel; (b) Removal
of approximately 300 Earth-masses of primordial gases from the Earth, which
began Earth's decompression process, making available the stored energy of
protoplanetary compression for driving geodynamic processes, which I have
described by the new whole-Earth decompression dynamics and which is
responsible for emplacing heat at the mantle-crust-interface at the base of the
crust through the process I have described, called mantle decompression
thermal-tsunami; and, (c)Uranium accumulations at the planetary centers capable
of self-sustained nuclear fission chain reactions.Comment: Invited paper for the Special Issue of Earth, Moon and Planets
entitled Neutrino Geophysics Added final corrections for publicatio
The 5′-untranslated region of the mouse mammary tumor virus mRNA exhibits cap-independent translation initiation
In this study, we demonstrate the identification of an internal ribosome entry site (IRES) within the 5′-untranslated region (5′-UTR) of the mouse mammary tumor virus (MMTV). The 5′-UTR of the full-length mRNA derived from the infectious, complete MMTV genome was cloned into a dual luciferase reporter construct containing an upstream Renilla luciferase gene (RLuc) and a downstream firefly luciferase gene (FLuc). In rabbit reticulocyte lysate, the MMTV 5′-UTR was capable of driving translation of the second cistron. In vitro translational activity from the MMTV 5′-UTR was resistant to the addition of m7GpppG cap-analog and cleavage of eIF4G by foot-and-mouth disease virus (FMDV) L-protease. IRES activity was also demonstrated in the Xenopus laevis oocyte by micro-injection of capped and polyadenylated bicistronic RNAs harboring the MMTV-5′-UTR. Finally, transfection assays showed that the MMTV-IRES exhibits cell type-dependent translational activity, suggesting a requirement for as yet unidentified cellular factors for its optimal function
Rochas ultramáficas plutônicas do greenstone belt Rio das Velhas na porção central do Quadrilátero Ferrífero, Minas Gerais, Brasil
Neue Beobachtungen an radioaktiven Höfen in verschiedenen Mineralien, mit kritischen Bemerkungen zur Auswertung der Höfe zur Altersbestimmung
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