Hyperfine Quenching of the 4s4p3P04s4p ^{3}P_{0} Level in Zn-like Ions

In this paper, we used the multiconfiguration Dirac-Fock method to compute with high precision the influence of the hyperfine interaction on the $[Ar]3d^{10} 4s4p ^3P_0$ level lifetime in Zn-like ions for stable and some quasi-stable isotopes of nonzero nuclear spin between Z=30 and Z=92. The influence of this interaction on the $[Ar]3d^{10} 4s4p ^3P_1 - [Ar]3d^{10} 4s4p ^3P_0$ separation energy is also calculated for the same ions

Analysis of X-ray spectra emitted from laser-produced plasmas of uranium

In this paper, we used the multiconfiguration Dirac-Fock method to generate theoretical X-ray spectra for Co-, Ni-, Cu-, Zn-, Ga-, Ge-, As-, Se-, Br-, Kr-, and Rb-like uranium ions. Using the distribution of these ions in a laser-produced plasma, for different plasma temperatures, we generate theoretical spectra, which are compared to experimental data

Sr and Nd isotope composition of the Alcáçovas calc-alkaline rocks (Ossa-Morena Zone, Portugal)

The Alcáçovas area is located in the SW sector of the Ossa-Morena Zone (OMZ), close to a major fault that separates this geotectonic unit from the South Portuguese Zone (SPZ). Along this boundary, in the OMZ, testimonies of low-K tholeiitic and calc-alkaline magmatism are common and have been interpreted as being related to the operation of a subduction zone between OMZ and SPZ during the Variscan cycle [1]. Two main igneous lithologies, both displaying calc-alkaline compositions, can be found in the studied area: gabbro-diorites and dacitic-rhyolitic porphyries [2,3]. Outcrop conditions have not yet allowed to establish unequivocally the sequence of magma emplacement. In previous geochronological studies on the porphyries, whole-rock Rb-Sr dates and K-Ar ages cluster around 320 Ma [4,5,6]. According to field observations, sometimes felsic dykes cut mafic rocks, but there are also gradual transitions from gabbroic to tonalitic compositions, within bodies mapped as gabbro-diorite, revealing that different melts coexisted. In this study, rock samples of both gabbro-dioritic bodies and porphyries were analysed for Rb-Sr and Sm-Nd isotopes. Considering the whole set of samples, no isochron was obtained, showing that they can not be simply related by crystal fractionation processes. Rb-Sr data of porphyries from a single quarry (at Lameira, 7 km to the SW of Alcáçovas) give 323±16 Ma (MSWD=1.9; initial 87Sr/86Sr=0.7097±0.0018). Taking into account that the rocks of the Lameira outcrop show strong hydrothermal alteration, this date must be viewed as a consequence of a very efficient redistribution of mobile elements during aqueous fluid circulation and, as such, it places a minimum limit to the actual magmatic age. The plot of compositions of the gabbro-dioritic bodies, including their transitions to tonalites and the associated felsic dykes, in the εNd-87Sr/86Sr diagram, define an almost perfect hyperbole (from εNd323 = +3.9 and 87Sr/86Sr323 = 0.7058 to εNd323 = -3.8 and 87Sr/86Sr323 = 0.7085), as expected in a mixture between mantle-derived melts and crustal materials. In the same diagram, samples from the Lameira quarry show an almost constant εNd323, between -2.4 and -2.9, and 87Sr/86Sr323 varying from 0.7092 to 0.7106. Therefore, the Lameira porphyries could represent a member of the same mixture, with the Sr signature modified by hydrothermal fluids with a stronger crustal component

Relativistic correlation correction to the binding energies of the ground configuration of Beryllium-like, Neon-like, Magnesium-like and Argon-like ions

Total electronic correlation correction to the binding energies of the isoelectronic series of Beryllium, Neon, Magnesium and Argon, are calculated in the framework of relativistic multiconfiguration Dirac-Fock method. Convergence of the correlation energies is studied as the active set of orbitals is increased. The Breit interaction is treated fully self-consistently. The final results can be used in the accurately determination of atomic masses from highly charged ions data obtained in Penning-trap experiments.Comment: version soumise 3/08/200

Glass/polyvinyl chloride composites

This paper summarizes the results obtained in the use of plastisols of vinyl chloride homopolymer (PVC), obtained by the process of emulsion polymerization, as thermoplastic matrix in the production of composite pipes and in pipe repairing. Two processing techniques commonly used with thermosetting matrices were studied: filament winding and hand lay-up. The produced composite structures of PVC reinforced with glass fibres were subsequently subjected to tests in order to determine their mechanical properties. This paper concludes that it is possible to use the described technique for piping repairing with good results

The Farol Deposit (Depósito do Farol) – a Pleistocene beach deposit from Cape Mondego (Figueira da Foz, West Central Portugal)*

Among the Pleistocene and Holocene units recorded near the marine cliffs of Cape Mondego (Figueira da Foz, West Central Portugal) stands out the Farol Deposit (Depósito do Farol), at an altitude of ±95 m above present sea level. It is a marine terrace with three exposures of interstratified conglomerates and sands, overlapped by calclititic-fanglomerates. This sedimentary setting indicates that deposition took place in a seashore environment influenced by the proximity of a marine palaeocliff. The deposit has an interesting subfossil fauna with abraded and fragmented shells of Nucella lapillus (LINNÉ, 1758), Patella vulgata (LINNÉ, 1758) and Littorina littorea (LINNÉ, 1758), suggesting the existence of an environment with colder surface seawater, when compared with the present day Portuguese seashore. These specimens belonged to marine communities adapted to live in intertidal rocky platforms, which have been exposed to the cyclic action of waves and tidal flows, on the swash and surf zones. The Farol Deposit can be related to an Early/Middle Pleistocene “cold-water” episode, earlier to the Isotopic Stages 7 and 11. This episode occurred before the deposition of the units Quiaios Sands (Areias de Quiaios) and Cantanhede Sands (Areias de Cantanhede) (Sicilian?), but later than the Arazede Sands (Areias de Arazede) and Marinha das Ondas Sands (Areias de Marinha das Ondas) (Early Pleistocene)

Gramíneas nativas de terra inundável do Tropico Úmido Brasileiro.

Características do ambiente amazônico das áreas de terra inundável. Gramíneas nativas de terra inundável. Desempenho animal.bitstream/item/60885/1/CPATU-Doc81.pd

Rediscovery of Leptaxis vetusta (Morelet & Drouet, 1857), a subfossil land snail from the Quaternary of Santa Maria (Azores)

During a recent field work on the southern coast of the island of Santa Maria (Azores) a bulk sample of 37 shells and 25 fragments of Leptaxis vetusta was assembled from Late Pleistocene and Holocene slope deposits outcropping in the area. These specimens are the first of this rare subfossil species to be mentioned since the original descriptions of Arthur Morelet and Henri Drouet (1857). The purposes of our paper are a systematic and biometric description of L. vestuta. For the first time, the original type: locality was localized with accuracy over the southern downslopes of Pico do Facho, between Figueiral and Prainha. The subfossil specimens were collected in slope deposits and detritic fans, overlying a fossiliferous marine deposit situated over the 2-3 m abrasion platform of Praia and Prainha bay. The age and factors associated to the extinction of this species are discussed, including the destruction of the original laurel cover and the colonization by Otala lactea (Muller, 1774), a continental helicid introduced and widespread in Santa Maria

Processing of continuous fibre reinforced thermoplastics

Towpregs based on different fibres and thermoplastic matrices were processed for highly demanding and more commercial applications by different composite processing technologies. In the technologies used, compression moulding and pultrusion, the final composite processing parameters were studied in order to obtain composites with adequate properties at industrial compatible production rates. The produced towpregs were tested to verify its polymer content and degree of impregnation. The obtained results have shown that the coating line enabled to produce, with efficiency and industrial scale speed rates, thermoplastic matrix towpregs that may be used to manufacture composites for advanced and larger volume commercial markets.(undefined