Exploration geochemistry in a shear-zone related Cu-Au-Hg district: Punitaqui, Chile

El distrito de Punitaqui se localiza en una zona montañosa semi árida de la Cordillera de la Costa de la región norte de Chile central. El distrito alberga una serie de mineralizaciones filonianas de Cu-Au-Hg, que se emplazan a lo largo del sector occidental de una zona de cizalla NNE de unos 200-400 m de potencia. La zona de cizalla separa a granitoides del Cretácico medio de una secuencia principalmente volcánica (andesitas y andesitas basálticas) de edad Valanginiense. Como base para la búsqueda de nuevas reservas en el distrito se realizaron estudios estructurales y geoquímicos. El estudio estructural indicó la existencia de fenómenos de superposición de una fábrica frágil sobre otra dúctil en la zona de cizalla, así como la existencia de una importante zona de transpresión. Se tomaron más de 160 muestras de suelo para el estudio geoquímico. Estas fueron recolectadas a lo largo del sector oeste de la zona de cizalla y a través de secciones perpendiculares a ésta. El estudio incluyó además 20 muestras de rocas, y 5 de minerales de mena. Las muestras se analizaron por 48 elementos, mediante extracción total. Adicionalmente, se analizaron 59 elementos por el método de extracción enzimática. Au, Cu, Ag, Hg, Sb, y As “totales”, así como el Au y el Sb “enzimáticos” probaron ser los mejores trazadores geoquímicos para la detección de cuerpos mineralizados no aflorantes. El estudio geoquímico permitió descartar sectores a lo largo de la zona de cizalla, restringiendo el interés a la parte norte (sector Culebra-Viña Vieja). Sondeos realizados en esta zona mostraron la existencia de recursos minerales (Au-Cu) del orden de los 9 Mt.The Punitaqui district is located within a hilly semiarid region of the Coastal Cordillera of northern central Chile. The district hosts Cu-Au-Hg vein deposits emplaced along the western side of a 200-400 m wide NNE trending shear zone. The shear zone separates a Middle Cretaceous granitoid from a mainly volcanic sequence (andesites and basaltic andesites) of Valanginian age. Exploration for new reserves in the district required detailed structural and geochemical works. The structural study of the shear zone allowed recognition of brittle-on-ductile overprinting (mylonite to breccia) phenomena along the shear zone, and the existence of a major restraining (contractional) bend within the district.Over 160 soil samples were taken for the geochemical study, both along the western side of the shear zone, and along sections cross-cutting the structure. The survey also included 20 samples from rocks and 5 from ores. The samples were analyzed for 48 elements (total extraction). Additionally, 59 elements were analized in the soil samples by the enzyme leach extraction technique. Total Au, Cu, Ag, Hg, Sb, and As, as well as ‘enzymatic’ Au and Sb proved to be the best tracers for hidden orebodies. The geochemical survey allowed definition of a major target in the northern part of the district (Culebra-Viña Vieja zone). A drilling campaign (DDH) showed the existence of gold copper mineral resources (9 Mt) in that zone.Depto. de Mineralogía y PetrologíaFac. de Ciencias GeológicasTRUEpu

Giant Magnetoresistance In Cluster-assembled Nanostructures: A Quantitative Approach

In a recent publication [1] we have discussed qualitatively the applicability of commonly used assumptions and models in the description of giant magnetoresistance in granular media by comparing to well-defined cluster-assembled nanostructures of cobalt clusters embedded in copper thin films. In this article we present a quantitative analysis and discuss the relevant parameters appearing in the model. © Published under licence by IOP Publishing Ltd.5211 Region Languedoc-Roussillon,Universite de Perpignan Via DomitiaOyarzún, S., Domingues Tavares De Sa, A., Tuaillon-Combes, J., Tamion, A., Hillion, A., Boisron, O., Mosset, A., Hillenkamp, M., (2013) J. Nanopart. Res., 15 (9), p. 1968. , 10.1007/s11051-013-1968-8 1388-0764Perez, A., Dupuis, V., Tuaillon-Combes, J., Bardotti, L., Prevel, B., Bernstein, E., Melinon, P., Jamet, M., Functionalized cluster-assembled magnetic nanostructures for applications to high integration-density devices (2005) Advanced Engineering Materials, 7 (6), pp. 475-485. , DOI 10.1002/adem.200400220Tamion, A., Hillenkamp, M., Tournus, F., Bonet, E., Dupuis, V., (2009) Appl Phys. Lett., 95 (6), p. 062503. , 10.1063/1.3200950 0003-6951Allia, P., Knobel, M., Tiberto, P., Vinai, F., (1995) Phys. Rev., 52 (21), pp. 15398-15411. , 10.1103/PhysRevB.52.15398 0163-1829 BBatlle, X., Labarta, A., (2002) J. Phys. D: Appl. Phys., 35 (6), pp. 15-R42. , 0022-3727 201Zhang, S., Levy, P.M., (1993) J. Appl. Phys., 73 (10), p. 5315. , 10.1063/1.353766 0021-8979Rubin, S., Holdenried, M., Micklitz, H., (1998) Eur. Phys. J., 5 (1), pp. 23-28. , 10.1007/s100510050414 1434-6028 BTamion, A., Hillenkamp, M., Tournus, F., Bonet, E., Dupuis, V., (2012) Appl. Phys. Lett., 100 (13), p. 136102. , 10.1063/1.3696891 0003-6951Henriquez, R., Cancino, S., Espinosa, A., Flores, M., Hoffmann, T., Kremer, G., Lisoni, J.G., Munoz, R.C., (2010) Phys. Rev., 82 (11), p. 113409. , 10.1103/PhysRevB.82.113409 1098-0121 BHenriquez, R., Moraga, L., Kremer, G., Flores, M., Espinosa, A., Munoz, R.C., (2013) Appl. Phys. Lett., 102 (5), p. 051608. , 10.1063/1.4791600 0003-695

Encapsulation of gold nanostructures and oil-in-water nanocarriers in microgels with biomedical potential

Indexación: Scopus.Funding: This research was funded by FONDECYT 1161450, 1150744, 11130494 and 1170929, FONDEQUIP EQM160157, EQM170111, CONICYT-FONDAP 15130011, and CONICYT PhD Scholarship 21141137.Here we report the incorporation of gold nanostructures (nanospheres or nanorods, functionalized with carboxylate-end PEG) and curcumin oil-in-water (O/W) nanoemulsions (CurNem) into alginate microgels using the dripping technique. While gold nanostructures are promising nanomaterials for photothermal therapy applications, CurNem possess important pharmacological activities as reported here. In this sense, we evaluated the effect of CurNem on cell viability of both cancerous and non-cancerous cell lines (AGS and HEK293T, respectively), demonstrating preferential toxicity in cancer cells and safety for the non-cancerous cells. After incorporating gold nanostructures and CurNem together into the microgels, microstructures with diameters of 220 and 540 µm were obtained. When stimulating microgels with a laser, the plasmon effect promoted a significant rise in the temperature of the medium; the temperature increase was higher for those containing gold nanorods (11–12 ◦ C) than nanospheres (1–2 ◦ C). Interestingly, the incorporation of both nanosystems in the microgels maintains the photothermal properties of the gold nanostructures unmodified and retains with high efficiency the curcumin nanocarriers. We conclude that these results will be of interest to design hydrogel formulations with therapeutic applications. © 2018 by the authors.https://www.mdpi.com/1420-3049/23/5/120

Earth Science Data Fusion with Event Building Approach

Objectives of the NASA Information And Data System (NAIADS) project are to develop a prototype of a conceptually new middleware framework to modernize and significantly improve efficiency of the Earth Science data fusion, big data processing and analytics. The key components of the NAIADS include: Service Oriented Architecture (SOA) multi-lingual framework, multi-sensor coincident data Predictor, fast into-memory data Staging, multi-sensor data-Event Builder, complete data-Event streaming (a work flow with minimized IO), on-line data processing control and analytics services. The NAIADS project is leveraging CLARA framework, developed in Jefferson Lab, and integrated with the ZeroMQ messaging library. The science services are prototyped and incorporated into the system. Merging the SCIAMACHY Level-1 observations and MODIS/Terra Level-2 (Clouds and Aerosols) data products, and ECMWF re- analysis will be used for NAIADS demonstration and performance tests in compute Cloud and Cluster environments

Changes in symptoms of asthma and rhinitis by sensitization status over ten years in a cohort of young Chilean adults

BACKGROUND: We investigated the net changes in prevalence of symptoms of asthma and rhinitis over 10 years in a cohort of young by baseline sensitization status. METHODS: One thousand one hundred ninety three Chilean adults subjects aged 22-28 living in a semi-rural area of central Chile answered a lifestyle and the European Community Respiratory Health Survey (ECRHS) questionnaires. Bronchial hyper-responsiveness (BHR) and skin prick test (SPT) to eight allergens were measured at baseline in 2001. Ten years later, 772 participants completed the questionnaires again. Estimates of adjusted net changes in prevalence of symptoms by sensitization status at baseline and association between sensitization status at baseline and respiratory symptoms ten years later were assessed. RESULTS: A quarter of the participants were sensitized to at least one allergen in 2001. Prevalence of wheeze had a net change per year of -0.37 % (95 % Confidence Interval -0.71 to 0.02 %; p = 0.067). Self-reported nasal allergies in the last 12 months increased by 0.83 % per year (95 % CI 0.49 to 1.17 %; p < 0.001). Those sensitized to either cat fur (OR 1.76; CI 1.01 to 3.05), cockroach, (OR 2.09; 1.13 to 3.86) blend of grass and pollens (1.78; 95 % CI 1.08 to 2.92), or weeds (OR 1.77; 95 % CI 1.01 to 3.12) in 2001 were more likely to have wheeze in the last 12 months 10 years later. CONCLUSION: Symptoms of asthma remained stable or slightly changed over 10 years in adults, whilst rhinitis and nasal allergies greatly increased. Being sensitized to at least one allergen is a risk factor for persistent symptoms of asthma and rhinitis, but not for determining net changes of symptoms over time. The underlying causes for the contrasting trends between asthma and nasal allergy are unknow

A MegaCam Survey of Outer Halo Satellites. I. Description of the Survey

We describe a deep, systematic imaging study of satellites in the outer halo of the Milky Way. Our sample consists of 58 stellar overdensities --- i.e., substructures classified as either globular clusters, classical dwarf galaxies, or ultra-faint dwarf galaxies --- that are located at Galactocentric distances of R$_{\rm GC}$ > 25 kpc (outer halo) and out to ~400 kpc. This includes 44 objects for which we have acquired deep, wide-field, $g-$ and $r-$band imaging with the MegaCam mosaic cameras on the 3.6m Canada-France-Hawaii Telescope and the 6.5m Magellan-Clay telescope. These data are supplemented by archival imaging, or published $gr$ photometry, for an additional 14 objects, most of which were discovered recently in the Dark Energy Survey (DES). We describe the scientific motivation for our survey, including sample selection, observing strategy, data reduction pipeline, calibration procedures, and the depth and precision of the photometry. The typical 5$\sigma$ point-source limiting magnitudes for our MegaCam imaging --- which collectively covers an area of ~52 deg$^{2}$ --- are $g_{\rm lim}$ ~25.6 and $r_{\rm lim}$ ~25.3 AB mag. These limits are comparable to those from the coadded DES images and are roughly a half-magnitude deeper than will be reached in a single visit with LSST. Our photometric catalog thus provides the deepest and most uniform photometric database of Milky Way satellites available for the foreseeable future. In other papers in this series, we have used these data to explore the blue straggler populations in these objects, their density distributions, star formation histories, scaling relations and possible foreground structures.Comment: Accepted for publication in Ap

A MegaCam Survey of Outer Halo Satellites. III. Photometric and Structural Parameters

We present structural parameters from a wide-field homogeneous imaging survey of Milky Way satellites carried out with the MegaCam imagers on the 3.6m Canada-France-Hawaii Telescope (CFHT) and 6.5m Magellan-Clay telescope. Our survey targets an unbiased sample of "outer halo" satellites (i.e., substructures having Galactocentric distances greater than 25 kpc) and includes classical dSph galaxies, ultra-faint dwarfs, and remote globular clusters. We combine deep, panoramic $gr$ imaging for 44 satellites and archival $gr$ imaging for 14 additional objects (primarily obtained with the DECam instrument as part of the Dark Energy Survey), to measure photometric and structural parameters for 58 outer halo satellites. This is the largest and most uniform analysis of Milky Way satellites undertaken to date and represents roughly three quarters ($58/81 \simeq$72\%) of all known outer halo satellites. We use a maximum-likelihood method to fit four density laws to each object in our survey: exponential, Plummer, King and Sersic models. We examine systematically the isodensity contour maps and color magnitude diagrams for each of our program objects, present a comparison with previous results, and tabulate our best-fit photometric and structural parameters, including ellipticities, position angles, effective radii, Sersic indices, absolute magnitudes, and surface brightness measurements. We investigate the distribution of outer halo satellites in the size-magnitude diagram, and show that the current sample of outer halo substructures spans a wide range in effective radius, luminosity and surface brightness, with little evidence for a clean separation into star cluster and galaxy populations at the faintest luminosities and surface brightnesses.Comment: Accepted for publication in Ap

Evidence for spin to charge conversion in GeTe(111)

GeTe has been predicted to be the father compound of a new class of multifunctional materials, ferroelectric Rashba semiconductors, displaying a coupling between spin-dependent k-splitting and ferroelectricity. In this paper, we report on epitaxial Fe/GeTe(111) heterostructures grown by molecular beam epitaxy. Spin-pumping experiments have been performed in a radio-frequency cavity by pumping a spin current from the Fe layer into GeTe at the Fe ferromagnetic resonance and detecting the transverse charge current originated in the slab due to spin-to-charge conversion. Preliminary experiments indicate that a clear spin to charge conversion exists, thus unveiling the potential of GeTe for spin-orbitronics

Petrogenesis of Eocene Tamazert continental carbonatites (Central High Atlas, Morocco): implications for a common source for the Tamazert and Canary and Cape Verde Island carbonatites

The Tamazert Eocene alkaline complex of the Central High Atlas Range of Morocco hosts the largest outcropping occurrences of carbonatites in northern Africa. The complex consists of carbonatites and undersaturated ultramafic to syenitic alkaline to peralkaline silicate rocks. Mineralogically and geochemically the Tamazert carbonatites are classified as calciocarbonatites, magnesiocarbonatites and silicocarbonatites.They are enriched in light rare earth elements and large ion lithophile elements (Cs, Rb, Ba, U,Th), but depleted in high field strength elements (particularly, Ti, Nb and Ta). Stable and radiogenic isotope ratios vary in the range of δ13CPDB=-5·8 to 1·8 0/00, δ18OSMOW=6·9-23·5 0/00, initial 87Sr/86Sr=0·7031-0·7076, 143Nd/144Nd=0·5125-0·5129 and 206Pb/204Pb=18·29-19·89. Calciocarbonatites intruding Jurassic limestones have the highest δ13C and δ18O values and the most radiogenic initial 87Sr/86Sr, but least radiogenic 143Nd/144Nd, 206Pb/204Pb and 208Pb/204Pb isotope ratios, and are interpreted to have interacted with the limestones (crustal components). The magnesio- and silicocarbonatites have Sr, Nd and Pb isotope ratios that are nearly identical to those of low-87Sr/86Sr calciocarbonatites. The isotope signature of the high-Sr, low-87Sr/86Sr calciocarbonatites with mantle-type O and C isotopic compositions indicates the presence of HIMU- and EMI-type components in the mantle source of the Tamazert carbonatites, similar to what has been proposed for the Cape Verde and Canary Islands.The close similarity in carbonatite composition between the Cape Verde and Canary Islands and Tamazert suggests a common sublithospheric source for these carbonatites. We therefore propose that theTamazert carbonatites originated through melting of Canary plume material that may have flowed through a sub-lithospheric corridor extending from the Atlantic near the Canary Islands to the Middle Atlas, formed by the delamination of the subcontinental lithosphere in response to Africa-Europe collision at c. 42Ma. Seismic tomography data suggest that the common source may be within the lower mantle at depths >1000 km

Spin-pumping into surface states of topological insulator {\alpha}-Sn, spin to charge conversion at room temperature

We present experimental results on the conversion of a spin current into a charge current by spin pumping into the Dirac cone with helical spin polarization of the elemental topological insulator (TI) {\alpha}-Sn[1-3]. By angle-resolved photoelectron spectroscopy (ARPES) we first confirm that the Dirac cone at the surface of {\alpha}-Sn (0 0 1) layers subsists after covering with Ag. Then we show that resonant spin pumping at room temperature from Fe through Ag into {\alpha}-Sn layers induces a lateral charge current that can be ascribed to the Inverse Edelstein Effect[4-5]. Our observation of an Inverse Edelstein Effect length[5-6] much longer than for Rashba interfaces[5-10] demonstrates the potential of the TI for conversion between spin and charge in spintronic devices. By comparing our results with data on the relaxation time of TI free surface states from time-resolved ARPES, we can anticipate the ultimate potential of TI for spin to charge conversion and the conditions to reach it.Comment: 14 pages, 5 figure