6,850 research outputs found
Preparación y caracterización de óxidos de manganeso no estequiométricos
Se describe la preparación y caracterización fisicoquÃmica por diversas técnicas (análisis quÃmico elemental, difracción de
rayos X, espectroscopÃa FT-IR, análisis térmico y determinación de superficie especÃfica) de birnesitas de Na, K y Li preparadas
por diversos métodos. Asimismo, se han estudiado sus propiedades de cambio iónico, caracterizando las muestras
intercambiadas por las mismas técnicas. Se ha encontrado que el intercambio es prácticamente total en el caso del Li, mientras
que en el caso de Cu y Mg el porcentaje intercambiado es relativamente bajo.Peer reviewe
New records of moths (Insecta, Lepidoptera) from urban gardens on Terceira Island with new data on recently introduced species to the Azores
The urban Duque da Terceira Garden, in the main town of Angra do HeroÃsmo (Terceira, Azores), was investigated to describe the species composition of moths (Insecta, Lepidoptera). Moths were sampled with two methods: SLAM traps (between April and September 2017) and light trapping (two sessions in the summer of 2017). A total of 42 taxa were sampled with the addition of 19 new records for Duque da Terceira Garden, five of which were also new records for Terceira Island. The five species recorded as new for Terceira were subjected to an exhaustive taxonomic analysis. In addition, we revised the colonization status of some species. Our results show that urban gardens may help the establishment of exotic species and that it is necessary to monitor and control how these species established in urban environments.info:eu-repo/semantics/publishedVersio
NGC 7331: the Galaxy with the Multicomponent Central Region
We present the results of the spectral investigation of the regular Sb galaxy
NGC 7331 with the Multi-Pupil Field Spectrograph of the 6m telescope. The
absorption-line indices H-beta, Mgb, and are mapped to analyse the
properties of the stellar populations in the circumnuclear region of the
galaxy. The central part of the disk inside ~3" (200 pc) -- or a separate
circumnuclear stellar-gaseous disk as it is distinguished by decoupled fast
rotation of the ionized gas -- is very metal-rich, rather young, ~ 2 billion
years old, and its solar magnesium-to-iron ratio evidences for a very long
duration of the last episode of star formation there. However the gas
excitation mechanism now in this disk is shock-like. The star-like nucleus had
probably experienced a secondary star formation burst too: its age is 5 billion
years, much younger than the age of the circumnuclear bulge. But [Mg/Fe]=+0.3
and only solar global metallicity imply that the nuclear star formation burst
has been much shorter than that in the circumnuclear disk. The surrounding
bulge is rather old, 9--14 billion years old, and moderately metal-poor. The
rotation of the stars and gas within the circumnuclear disk is axisymmetric
though its rotation plane may be slightly inclined to the global plane of the
galaxy. Outside the circumnuclear disk the gas may experience non-circular
motions, and we argue that the low-contrast extended bulge of NGC 7331 is
triaxial.Comment: LATEX, 27 pages, + 15 Postscript figures. Accepted to Astronomical
Journal, July issu
LEIR electron cooler status
The electron cooler for LEIR is the first of a new generation of coolers being commissioned for fast phase space cooling of ion beams in storage rings. It is a stateof- the-art cooler incorporating all the recent developments in electron cooling technology (adiabatic expansion, electrostatic bend, variable density electron beam) and is designed to deliver up to 600 mA of electron current for the cooling and stacking of Pb54+ ions in the frame of the ions for LHC project. In this paper we present our experience with the commissioning of the new device as well as the first results of ion beam cooling with a high-intensity variable-density electron beam
Measurement of the intrinsic damping constant in individual nanodisks of YIG and YIG{\textbar}Pt
We report on an experimental study on the spin-waves relaxation rate in two
series of nanodisks of diameter 300, 500 and 700~nm, patterned out of
two systems: a 20~nm thick yttrium iron garnet (YIG) film grown by pulsed laser
deposition either bare or covered by 13~nm of Pt. Using a magnetic resonance
force microscope, we measure precisely the ferromagnetic resonance linewidth of
each individual YIG and YIG{\textbar}Pt nanodisks. We find that the linewidth
in the nanostructure is sensibly smaller than the one measured in the extended
film. Analysis of the frequency dependence of the spectral linewidth indicates
that the improvement is principally due to the suppression of the inhomogeneous
part of the broadening due to geometrical confinement, suggesting that only the
homogeneous broadening contributes to the linewidth of the nanostructure. For
the bare YIG nano-disks, the broadening is associated to a damping constant
. A 3 fold increase of the linewidth is observed for
the series with Pt cap layer, attributed to the spin pumping effect. The
measured enhancement allows to extract the spin mixing conductance found to be
for our
YIG(20nm){\textbar}Pt interface, thus opening large opportunities for the
design of YIG based nanostructures with optimized magnetic losses.Comment: 4 pages, 3 figure
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