Small hypervelocity particles captured in aerogel collectors: Location,extraction, handling and storage     

Andrew J. Westphal  Christopher Snead  Janet Borg  Eric Quirico  Pierre‐Ivan Raynal  Michael E. Zolensky  Gianluca Ferrini  Luigi Colangeli  Pasquale Palumbo 《Meteoritics & planetary science》2002,37(6):855-865

Abstract— It has now been about a decade since the first demonstrations that hypervelocity particles could be captured, partially intact, in aerogel collectors. But the initial promise of a bonanza of partially‐intact extraterrestrial particles, collected in space, has yet to materialize. One of the difficulties that investigators have encountered is that the location, extraction, handling and analysis of very small (10 μm and less) grains, which constitute the vast majority of the captured particles, is challenging and burdensome. Furthermore, current extraction techniques tend to be destructive over large areas of the collectors. Here we describe our efforts to alleviate some of these difficulties. We have learned how to rapidly and efficiently locate captured particles in aerogel collectors, using an automated microscopic scanning system originally developed for experimental nuclear astrophysics. We have learned how to precisely excavate small access tunnels and trenches using an automated micromanipulator and glass microneedles as tools. These excavations are only destructive to the collector in a very small area—this feature may be particularly important for excavations in the precious Stardust collectors. Using actuatable silicon microtweezers, we have learned how to extract and store “naked” particles—essentially free of aerogel—as small as 3 μm in size. We have also developed a technique for extracting particles, along with their terminal tracks, still embedded in small cubical aerogel blocks. We have developed a novel method for storing very small particles in etched nuclear tracks. We have applied these techniques to the extraction and storage of grains captured in aerogel collectors (Particle Impact Experiment, Orbital Debris Collector Experiment, Comet‐99) in low Earth orbit.  相似文献   

The fundamental plane of ellipticals – I. The dark matter connection     

Annamaria Borriello  Paolo Salucci  Luigi Danese 《Monthly notices of the Royal Astronomical Society》2003,341(4):1109-1120

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Transforming observational data and theoretical isochrones into the ACS/WFC Vega-mag system     

Luigi R. Bedin †  Santi Cassisi  Fiorella Castelli  Giampaolo Piotto  Jay Anderson  Maurizio Salaris  Yazan Momany  Adriano Pietrinferni 《Monthly notices of the Royal Astronomical Society》2005,357(3):1038-1048

We propose a zero-point photometric calibration of the data from the Advanced Camera for Surveys (ACS) Wide Field Channel (WFC) on board the Hubble Space Telescope , based on a spectrum of Vega and the most up-to-date in-flight transmission curves of the camera. This calibration is accurate at the level of a few hundredths of a magnitude. The main purpose of this effort is to transform the entire set of evolutionary models into a simple observational photometric system for ACS/WFC data, and to make them available to the astronomical community. We provide the zero-points for the most used ACS/WFC bands, and give basic recipes for calibrating both the observed data and the models. We also present the colour–magnitude diagram from ACS data of five Galactic globular clusters, spanning the metallicity range  −2.2 <[Fe/H] < −0.04  , and we provide fiducial points representing their sequences from several magnitudes below the turn-off to the red giant branch tip. The observed sequences are compared with the models in the newly defined photometric system.  相似文献   

Petrogenesis and tectonic significance of Jurassic IAT magma types in the Hellenide ophiolites as deduced from the Rhodiani ophiolites (Pelagonian zone, Greece)   总被引：1，自引：0，他引：1  

Emilio Saccani  Adonis Photiades  Luigi Beccaluva   《Lithos》2008,104(1-4):71-84

The Rhodiani ophiolites are represented by two tectonically superimposed ophiolitic units: the “lower” Ultramafic unit and the “upper” Volcanic unit, both bearing calcareous sedimentary covers. The Ultramafic unit consists of mantle harzburgites with dunite pods and chromitite ores, and represents the typical mantle section of supra-subduction zone (SSZ) settings. The Volcanic unit is represented by a sheeted dyke complex overlain by a pillow and massive lava sequence, both including basalts, basaltic andesites, andesites, and dacites. Chemically, the Volcanic unit displays low-Ti affinity typical of island arc tholeiite (IAT) ophiolitic series from SSZ settings, having, as most distinctive chemical features, low Ti/V ratios (< 20) and depletion in high field strength elements and light rare earth elements.The rare earth element and incompatible element composition of the more primitive basaltic andesites from the Rhodiani ophiolites can be successfully reproduced with about 15% non-modal fractional melting of depleted lherzolites, which are very common in the Hellenide ophiolites. The calculated residua correspond to the depleted harzburgites found in the Rhodiani and Othrys ophiolites. Both field and chemical evidence suggest that the whole sequence of the Rhodiani Volcanic unit (from basalt to dacite) originated by low-pressure fractional crystallization under partially open-system conditions. The modelling of mantle source, melt generation, and mantle residua carried out in this paper provides new constraints for the tectono-magmatic evolution of the Mirdita–Pindos oceanic basin.  相似文献   

The double solid reactant method: II. An application to the shallow groundwaters of the Porto Plain,Vulcano Island (Italy)     

Matteo Lelli  Roberto Cioni  Luigi Marini 《Environmental Geology》2008,56(1):139-158

This paper presents an example of application of the double solid reactant method (DSRM) of Accornero and Marini (Environmental Geology, 2007a), an effective way for modeling the fate of several dissolved trace elements during water–rock interaction. The EQ3/6 software package was used for simulating the irreversible water–rock mass transfer accompanying the generation of the groundwaters of the Porto Plain shallow aquifer, starting from a degassed diluted crateric steam condensate. Reaction path modeling was performed in reaction progress mode and under closed-system conditions. The simulations assumed: (1) bulk dissolution (i.e., without any constraint on the kinetics of dissolution/precipitation reactions) of a single solid phase, a leucite-latitic glass, and (2) precipitation of amorphous silica, barite, alunite, jarosite, anhydrite, kaolinite, a solid mixture of smectites, fluorite, a solid mixture of hydroxides, illite-K, a solid mixture of saponites, a solid mixture of trigonal carbonates and a solid mixture of orthorhombic carbonates. Analytical concentrations of major chemical elements and several trace elements (Cr, Mn, Fe, Ni, Cu, Zn, As, Sr and Ba) in groundwaters were satisfactorily reproduced. In addition to these simulations, similar runs for a rhyolite, a latite and a trachyte permitted to calculate major oxide contents for the authigenic paragenesis which are comparable, to a first approximation, with the corresponding data measured for local altered rocks belonging to the silicic, advanced argillic and intermediate argillic alteration facies. The important role played by both the solid mixture of trigonal carbonates as sequestrator of Mn, Zn, Cu and Ni and the solid mixture of orthorhombic carbonates as scavenger of Sr and Ba is emphasized.

Luigi Marini (Corresponding author)Email:

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Polycyclic aromatic hydrocarbons in water, seston and copepods in a harbour area in the Western Mediterranean (Ligurian Sea)   总被引：2，自引：0，他引：2  

Luigi Pane  Simona Boccardo  Fabio Bonfiglioli  Gian Luigi Mariottini  Francesca Priano  & Osvaldo Conio 《Marine Ecology》2005,26(2):89-99

Polycyclic aromatic hydrocarbons (PAHs) are widespread carcinogenic, mutagenic and teratogenic pollutants that can significantly affect ecosystems and exert an influence on marine planktonic and benthic communities as well as on higher organisms such as fish and mammals, including humans. In this paper the concentrations of six PAHs in water, seston and copepods were examined in a harbour zone of the Genova Gulf (Ligurian Sea) from November 1997 to June 1998. The importance of freshwater inputs coming from a polluted stream and the influence of seasonal and atmospheric factors were also considered. Highest PAH values were recorded during spring. Fluoranthene, Benzo[b]fluoranthene and Benzo[k]fluoranthene were the most abundant PAHs either in water, seston or copepods. The concentration of total PAHs in seawater was often lower than the detection limit: recorded values ranged between 0.001 and 0.06 ppb. In seston, total PAHs ranged between 0.033 and 6.26 ng·g^?1 and in copepods between 0.01 and 2.34 ng·g^?1. With this study, PAH contamination in the harbour zone of Genova Sestri‐Ponente and the importance of inputs of organic pollutants coming from land and freshwaters have been emphasized.  相似文献   

Low multipath antennas for GNSS-based attitude determination systems applied to high-altitude platforms   总被引：1，自引：1，他引：0  

Luigi Boccia  Pasquale Pace  Giandomenico Amendola  Giuseppe Di Massa 《GPS Solutions》2008,12(3):163-171

High-altitude platforms (HAPs) are a flexible and attractive technology for providing innovative wireless services. These aerial platforms can be successfully employed for mobile or broadband communications and for disaster monitoring or response. However, one of the open issues is whether HAP stations can provide reliable services without temporal outages owing to stratospheric winds that can cause positional and attitude instabilities thus affecting the communication system operation. To counteract this issue, one possible solution is to use reconfigurable antennas whose pointing direction can be adjusted depending on the platform spatial orientation. However, this would require real-time three-axial attitude data. As a possible solution, this paper will review the potential of GNSS-based attitude determination systems with reference to HAP stations. In particular, it will be shown how the use of a particular class of low multipath and lightweight antennas can provide a high degree of accuracy without altering the avionic ballast.  相似文献   

Deformation mechanisms, microstructure and rheology of rocks in nature and experiment     

Neil S. Mancktelow  Luigi Burlini  Stefan M. Schmalholz  Karsten Kunze   《Tectonophysics》2006,427(1-4)

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Local pattern of stress field and seismogenic sources in the Pergola–Melandro basin and the Agri valley (Southern Italy)     

Luigi Cucci  Silvia Pondrelli  Alberto Frepoli  Maria Teresa Mariucci  Marco Moro 《Geophysical Journal International》2004,156(3):575-583

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Magma generation and crustal accretion as evidenced by supra-subduction ophiolites of the Albanide–Hellenide Subpelagonian zone     

Luigi  Beccaluva  Massimo  Coltorti  Emilio  Saccani  Franca  Siena 《Island Arc》2005,14(4):551-563

Abstract Ophiolites of the Mirdita–Subpelagonian zone form a nearly continuous belt in the Albanide–Hellenide orogen, including mid‐ocean ridge basalt (MORB) associations in the western Mirdita sector and supra‐subduction zone (SSZ) complexes, with prevalent island arc tholeiitic (IAT) and minor boninitic affinities in the eastern part of the belt (i.e. eastern Mirdita, Pindos, Vourinos). In addition, basalts with geochemical features intermediate between MORB and IAT (MORB/IAT) are found in the central Mirdita and in the Aspropotamos sequence (Pindos). These basalts alternate with pure MORB and are cut by boninitic dykes. The distinctive compositional characteristics of the mafic magmas parental to the different ophiolitic suites can be accounted for by partial melting of mantle sources progressively depleted by melt extractions. Partial melting processes (10–20%) of lherzolitic sources generated pure MORB, leaving clinopyroxene‐poor lherzolite as a residuum. Approximately 10% water‐assisted partial melting of this latter source, in an SSZ setting, may in turn generate basalts with MORB/IAT intermediate characteristics, whereas IAT basalts and boninites may have been derived from 10–20% and 30% partial melting, respectively, of the same source variably enriched by subduction‐derived fluids. In addition, boninites may also have been derived by comparatively lower degrees of hydrated partial melting of more refractory harzburgitic sources. A generalized petrologic model based on mass balance calculations between bulk rock and mineral compositions, indicate that most of the intrusives (from ultramafic cumulates to gabbronorites and plagiogranites), as well as sheeted dykes and volcanics (from basalts to rhyodacites) forming the bulk crustal section of the SSZ ophiolites, may be accounted for by shallow fractional crystallization from low‐Ti picritic parental magmas very similar in composition to IAT picrites from Pacific intraoceanic arcs. The most appropriate tectono‐magmatic model for the generation of the SSZ Tethyan ophiolites implies low velocity plate‐convergence of the intraoceanic subduction and generation of a nascent arc with IAT affinity and progressive slab roll‐back, mantle diapirism and extension from the arc axis to the forearc region, with generation of MORB/IAT intermediate basalts and boninitic magmas.  相似文献