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Fine tuning the ionic liquidâvacuum outer atomic surface using ion mixtures
Ionic liquidâvacuum outer atomic surfaces can be created that are remarkably different from the bulk composition. In this communication we demonstrate, using low-energy ion scattering (LEIS), that for ionic liquid mixtures the outer atomic surface shows significantly more atoms from anions with weaker cationâanion interactions (and vice versa)
HCG 16 Revisited: Clues About Galaxy Evolution in Groups
We present new spectroscopic observations of 5 galaxies, members of the
unusually active compact group HCG 16, observed using the Palomar 5m telescope.
The high signal to noise ratios (S/N ) of the spectra allow us to
study the variation of the emission line characteristics and the stellar
populations in the nucleus and the circumnuclear regions of the galaxies. The
emission line characteristics of these galaxies are complex, varying between
Seyfert 2 and LINERs or between LINERs and starbursts. All of the galaxies show
traces of intermediate age stellar populations, supporting our previous result
that post-starburst galaxies are common in compact groups. The galaxies
HCG16--4 and HCG16--5 show double nuclei and therefore could be two cases of
recent merger. Our observations support a scenario where HCG 16 was formed by
the successive merger of metal poor, low mass galaxies. The galaxies HCG16--1
and HCG16--2, which are more evolved, form the old core of the group. Galaxies
HCG16--4 and HCG16--5 are two more recent additions still in a merging phase.
Galaxy HCG16--5 is a starburst galaxy which is just beginning to fall into the
core. If HCG 16 is representative of compact groups in their early stage, the
whole set of observations implies that the formation of compact groups is the
result of hierarchical galaxy formation. HCG 16 could be one example of this
process operating in the local universe.Comment: tar file containing text and figures is available at
http://www.daf.on.br/~reinaldo/paper.htm
LINER/H II "Transition" Nuclei and the Nature of NGC 4569
Motivated by the discovery of young, massive stars in the nuclei of some
LINER/H II ``transition'' nuclei such as NGC 4569, we have computed
photoionization models to determine whether some of these objects may be
powered solely by young star clusters rather than by accretion-powered active
nuclei. The models were calculated with the photoionization code CLOUDY, using
evolving starburst continua generated by the the STARBURST99 code of Leitherer
et al. (1999). We find that the models are able to reproduce the emission-line
spectra of transition nuclei, but only for instantaneous bursts of solar or
higher metallicity, and only for ages of ~3-5 Myr, the period when the
extreme-ultraviolet continuum is dominated by emission from Wolf-Rayet stars.
For clusters younger than 3 Myr or older than 6 Myr, and for models with a
constant star-formation rate, the softer ionizing continuum results in an
emission spectrum more typical of H II regions. This model predicts that
Wolf-Rayet emission features should appear in the spectra of transition nuclei.
While such features have not generally been detected to date, they could be
revealed in observations having higher spatial resolution. Demographic
arguments suggest that this starburst model may not apply to the majority of
transition nuclei, particularly those in early-type host galaxies, but it could
account for some members of the transition class in hosts of type Sa and later.
The starburst models during the Wolf-Rayet-dominated phase can also reproduce
the narrow-line spectra of some LINERs, but only under conditions of
above-solar metallicity and only if high-density gas is present (n_e >~ 10^5
cm^{-3}). This scenario could be applicable to some ``Type 2'' LINERs which do
not show any clear signs of nonstellar activity.Comment: To appear in PASP. 22 pages, includes 9 figures, uses AASTeX v5.
Dashboard for the VISIR remote lab
The VISIR dashboard (VISIR-DB) is a learning analytics tool connected with the VISIR remote lab. In VISIR, every action performed by a student from the interface over the remote laboratory and back is logged and recorded. VISIR-DB helps visualizing, in a fast and deep way, the recorded logs from this communication. Using this tool, a teacher can analyze and understand better how the students are using the remote lab during their learning process on analog electronics. With this information, the VISIR platform can be improved and the use of remote labs can be better understood.The authors acknowledge the support provided by the European Project PILAR. Platform Integration of Laboratories based on the Architecture of visiR - Erasmus+ Strategic Partnership nÂș 2016-1-ES01-KA203-025327info:eu-repo/semantics/publishedVersio
Molecular elucidation of CO2 methanation over a highly active, selective and stable LaNiO3/CeO2-derived catalyst by in situ FTIR and NAP-XPS
The CO2 methanation mechanism over the highly active (TOF=75.1 hâ1), selective (>92%) and stable 10% LaNiO3/CeO2-derived catalyst is still unresolved. The surface of the catalyst is monitored under hydrogenation (H2), oxidizing (CO2) and CO2 methanation (H2 +CO2) conditions by near ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) using synchrotron radiation. Meanwhile, the main reaction intermediates are identified by in situ FTIR analysis. NAP-XPS experiments confirm that LaNiO3 perovskite reduction leads to the ex-solution of Ni0 nanoparticles and Ni2+single bondCeO2âx and Ni2+single bondLa2O3 interfaces conformation, favouring the CO2 adsorption and the H2 dissociation/transfer. In situ FTIR experiments combined with the C1s spectra (NAP-XPS) suggest that the CO2 activation occurs on CeO2âx (oxygen vacancies and OHâ) at low temperatures, in the form of bicarbonates; whereas, mono-/bidentate carbonates are formed on different strength La2O3 sites at increasing temperatures. These species are consecutively reduced to formates, as the main reaction intermediate, and methane by the H spilled from Ni0 nanoparticles near to NiOsingle bondCeO2âx and NiOsingle bondLa2O3 interfaces.Support for this study was provided by Projects PID2019â105960RB-C21 and PID2019â105960RB-C22 by MCIN/AEI/10.13039/501100011033, the Basque Government (Project IT1509â2022), Generalitat Valenciana (CIPROM/2021/74) and ALBA synchrotron. One of the authors (JAOC) acknowledges the postdoctoral research grant (DOCREC20/49) provided by the University of the Basque Country (UPV/EHU)
Recent results from the canfranc dark matter search with germanium detectors
Two germanium detectors are currently operating in the Canfranc Underground
Laboratory at 2450 m.w.e looking for WIMP dark matter. One is a 2 kg 76Ge IGEX
detector (RG-2) which has an energy threshold of 4 keV and a low-energy
background rate of about 0.3 c/keV/kg/day. The other is a small (234 g) natural
abundance Ge detector (COSME), of low energy threshold (2.5 keV) and an energy
resolution of 0.4 keV at 10 keV which is looking for WIMPs and for solar
axions. The analysis of 73 kg-days of data taken by COSME in a search for solar
axions via their photon Primakoff conversion and Bragg scattering in the Ge
crystal yields a 95% C.L. limit for the axion-photon coupling g < 2.8 10^-9
GeV^-1. These data, analyzed for WIMP searches provide an exclusion plot for
WIMP-nucleon spin-independent interaction which improves previous plots in the
low mass region. On the other hand, the exclusion plot derived from the 60
kg-days of data from the RG-2 IGEX detector improves the exclusion limits
derived from other ionization (non thermal) germanium detector experiments in
the region of WIMP masses from 30 to 100 GeV recently singled out by the
reported DAMA annual modulation effect.Comment: 6 pages, talk given at IDM2000, York, September 200
Solvothermal synthesis and characterization of ytterbium/iron mixed oxide nanoparticles with potential functionalities for applications as multiplatform contrast agent in medical image techniques
A solvothermal route to prepare Glutathione capped hybrid ytterbium/iron oxide nanoparticles with potential applications as multiplatform contrast agent in medical image techniques has been developed. The influence of ytterbium/iron molar ratio used as precursor, as well as the degree of the autoclave filling on the structural and morphological characteristics of the obtained nanoparticles has been extensively studied. Although all nanoparticles present similar composition, with YbFeO3 being the majority phase, size and morphology of the as synthetized nanoparticles are highly influenced by the critical temperature and by the over -saturation reached during the solvothermal process. We have demonstrated that glutathione properly functionalizes the hybrid nanoparticles, increasing their colloidal stability and decreasing their cytotoxicity. Additionally, they show good imaging in magnetic resonance and X-ray computerized tomography, thereby indicating promising potential as a dual contrast agent. This work presents, for the first time, glutathione functionalized ytterbium/iron oxide nanoparticles with potential applications in Biomedicine. © 2022 Elsevier Ltd and Techna Group S.r.l
Young Planetary Nebulae: Hubble Space Telescope Imaging and a New Morphological Classification System
Using Hubble Space Telescope images of 119 young planetary nebulae, most of
which have not previously been published, we have devised a comprehensive
morphological classification system for these objects. This system generalizes
a recently devised system for pre-planetary nebulae, which are the immediate
progenitors of planetary nebulae (PNs). Unlike previous classification studies,
we have focussed primarily on young PNs rather than all PNs, because the former
best show the influences or symmetries imposed on them by the dominant physical
processes operating at the first and primary stage of the shaping process.
Older PNs develop instabilities, interact with the ambient interstellar medium,
and are subject to the passage of photoionization fronts, all of which obscure
the underlying symmetries and geometries imposed early on. Our classification
system is designed to suffer minimal prejudice regarding the underlying
physical causes of the different shapes and structures seen in our PN sample,
however, in many cases, physical causes are readily suggested by the geometry,
along with the kinematics that have been measured in some systems. Secondary
characteristics in our system such as ansae indicate the impact of a jet upon a
slower-moving, prior wind; a waist is the signature of a strong equatorial
concentration of matter, whether it be outflowing or in a bound Keplerian disk,
and point symmetry indicates a secular trend, presumably precession, in the
orientation of the central driver of a rapid, collimated outflow.Comment: (to appear in The Astronomical Journal, March 2011.) The quality of
the figures as it appears in the arXiv pdf output is not up-to-par; the full
ms with high-quality figures is available by anonymous FTP at
ftp://ftp.astro.ucla.edu/pub/morris/sahai_AJ_360163.pd
Status of IGEX dark matter search at Canfranc Underground Laboratory
One IGEX 76Ge double-beta decay detector is currently operating in the
Canfranc Underground Laboratory in a search for dark matter WIMPs, through the
Ge nuclear recoil produced by the WIMP elastic scattering. In this talk we
report on the on-going efforts to understand and eventually reject the
background at low energy. These efforts have led to the improvement of the
neutron shielding and to partial reduction of the background, but still the
remaining events are not totally identified. A tritium contamination or
muon-induced neutrons are considered as possible sources, simulations and
experimental test being still under progress. According to the success of this
study we comment the prospects of the experiment as well as those of its future
extension, the GEDEON dark matter experiment.Comment: 6 pages, 3 figures, talk given at 4th International Workshop on the
Identification of Dark Matter, York, September 200
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