270 research outputs found
Ultra-deep 31.0-50.3 GHz spectral survey of IRC+10216
51 pags., 43 figs., 3 tabs.Context. The carbon-rich envelope of the asymptotic giant branch star CW Leo, IRC+10216, is one of the richest molecular sources in the sky. Available spectral surveys below 51 GHz are more than 25 years old, and new work is needed. Aims. Characterizing the rich molecular content of this source, specially for heavy species, requires carrying out very sensitive spectral surveys at low frequencies. In particular, we have achieved an rms in the range 0.2-0.6mK per MHz. Methods. Long Q band (31.0-50.3 GHz) single-dish integrations were carried out with the Yebes-40m telescope using specifically built receivers. The most recent line catalogs were used to identify the lines. Results. The data contain 652 spectral features, corresponding to 713 transitions from 81 species (we count the isomers, isotopologs, and ortho/para species separately). Only 57 unidentified lines remain with signal-to-noise ratios ≤3. Some new species and/or vibrational modes have been discovered for the first time with this survey. Conclusions. This IRC+10216 spectral survey is by far the most sensitive survey carried out to date in the Q band. It therefore provides the most complete view of IRC+10216 from 31.0 to 50.3 GHz, giving unique information about its molecular content, especially for heavy species. Rotational diagrams built from the data provide valuable information about the physical conditions and chemical content of this circumstellar envelope.We thank Ministerio de Ciencia e Innovación of Spain
for funding support through projects PID2019-106110GB-I00, PID2019-
107115GB-C21/AEI/10.13039/501100011033, PID2019-106235GB-I00, and
grant FJCI-2016-27983 for CB. We also thank ERC for funding through grant
ERC-2013-Syg-610256-NANOCOSMOS. M.A. thanks MICIU for grant RyC2014-16277
Laboratory Characterization and Astrophysical Detection of Vibrationally Excited States of Vinyl Cyanide in Orion-KL
New laboratory data of CHCHCN (vinyl cyanide) in its ground and
vibrationally excited states at the microwave to THz domain allow searching for
these excited state transitions in the Orion-KL line survey.
Frequency-modulated spectrometers combined into a single broadband 50-1900 GHz
spectrum provided measurements of CHCHCN covering a spectral range of
18-1893 GHz, whose assignments was confirmed by Stark modulation spectra in the
18-40 GHz region and by ab-initio anharmonic force field calculations. For
analyzing the emission lines of CHCHCN species detected in Orion-KL we used
the excitation and radiative transfer code (MADEX) at LTE conditions. The
rotational transitions of the ground state of this molecule emerge from four
cloud components of hot core nature which trace the physical and chemical
conditions of high mass star forming regions in the Orion-KL Nebula. The total
column density of CHCHCN in the ground state is (3.00.9)x10
cm. We report on the first interstellar detection of transitions in the
v10=1/(v11=1,v15=1) dyad in space, and in the v11=2 and v11=3 states in
Orion-KL. The lowest energy vibrationally excited states of vinyl cyanide such
as v11=1 (at 328.5 K), v15=1 (at 478.6 K), v11=2 (at 657.8 K), the
v10=1/(v11=1,v15=1) dyad (at 806.4/809.9 K), and v11=3 (at 987.9 K) are
populated under warm and dense conditions, so they probe the hottest parts of
the Orion-KL source. Column density and rotational and vibrational temperatures
for CHCHCN in their ground and excited states, as well as for the
isotopologues, have been constrained by means of a sample of more than 1000
lines in this survey. Moreover, we present the detection of methyl isocyanide
(CHNC) for the first time in Orion-KL and a tentative detection of vinyl
isocyanide (CHCHNC) and give column density ratios between the cyanide and
isocyanide isomers.Comment: 46 pages, 22 figures, 14 tables, 9 online table
Beam Mode Expansion of Corrugated Conical Horns with Phase Correcting Lens: Application to Radioastronomy Receivers
A classical radioastronomy receiver is fed with a corrugated horn and an independent lens,
both placed in a cryostat to lower the noise temperature. The beam is focused and directed using a
combination of elliptical and plane mirrors. This paper proposes modifying the initial feeding system
by placing the lens onto the horn aperture, thereby allowing a size reduction of the horn and lens, and a
simplification of their mechanical design. The profiled lens is shaped to correct the phase error on the
horn aperture. A quasi-optical model of the horn-plus-lens system has been developed using a Beam
Mode Expansion (BME). Results using both a hyperbolic-planar lens and a spherical-elliptical lens,
as well as results obtained by using Geometrical Optics (GO) with a Kirchoff–Huygens integration
to get the far-field pattern, have been compared with measurements. As a direct application, a full
focusing system for the new 40-m radiotelescope at the “Centro Astron´omico de Yebes” is presented
for the 22, 30 and 45 GHz bands. This paper has developed a QO model for a corrugated conical horn
with a phase-correcting lens
Beam Mode Expansion of Corrugated Conical Horns with Phase Correcting Lens: Application to Radioastronomy Receivers
A classical radioastronomy receiver is fed with a corrugated horn and an independent lens,
both placed in a cryostat to lower the noise temperature. The beam is focused and directed using a
combination of elliptical and plane mirrors. This paper proposes modifying the initial feeding system
by placing the lens onto the horn aperture, thereby allowing a size reduction of the horn and lens, and a
simplification of their mechanical design. The profiled lens is shaped to correct the phase error on the
horn aperture. A quasi-optical model of the horn-plus-lens system has been developed using a Beam
Mode Expansion (BME). Results using both a hyperbolic-planar lens and a spherical-elliptical lens,
as well as results obtained by using Geometrical Optics (GO) with a Kirchoff–Huygens integration
to get the far-field pattern, have been compared with measurements. As a direct application, a full
focusing system for the new 40-m radiotelescope at the “Centro Astron´omico de Yebes” is presented
for the 22, 30 and 45 GHz bands. This paper has developed a QO model for a corrugated conical horn
with a phase-correcting lens
La memoria: documento expansivo de la información contable de naturaleza externa
Desde la publicación del PGC-90 se han aprobado distintos planes sectoriales que han supuesto adecuar, a cada una de estas realidades, las normas generales de elaboración de información contable de naturaleza, principalmente, externa. Los cambios introducidos han significado la incorporación de criterios de valoración alternativos, la creación o modificación de ciertas cuentas a utilizar de forma específica, la adecuación de los modelos de balance y cuenta de pérdidas y ganancias y, sobre todo, la incorporación de información adicional en la memoria, respecto de la exigida con carácter general en el PGC-90
Evaluation of the inflammatory and osteogenic response induced by titanium particles released during implantoplasty of dental implants
Implantoplasty is a mechanical decontamination technique that consists of removing the threads and polishing and smoothing the dental implant surface. During implantoplasty there is a large release of titanium metal particles that might provoke a proinflammatory response and reduce the viability of osteogenic cells. We analyze the inflammatory and osteogenic response induced by Ti6Al4V particles released during implantoplasty and by as-received commercially pure Ti particles. Macrophages stimulated with metal particles obtained by implantoplasty and with as-received Ti particles showed an increased proinflammatory expression of TNF-alpha and a decreased expression of TGF-beta and CD206. Regarding cytokine release, there was an increase in IL-1 beta, while IL-10 decreased. The osteogenic response of Ti6Al4V extracts showed a significant decrease in Runx2 and OC expression compared to the controls and commercially pure Ti extracts. There were no relevant changes in ALP activity. Thus, implantoplasty releases metal particles that seems to induce a pro-inflammatory response and reduce the expression of osteogenic markers
Using radio astronomical receivers for molecular spectroscopic characterization in astrochemical laboratory simulations: A proof of concept
We present a proof of concept on the coupling of radio astronomical receivers
and spectrometers with chemical reactorsand the performances of the resulting
setup for spectroscopy and chemical simulations in laboratory astrophysics.
Several experiments including cold plasma generation and UV photochemistry were
performed in a 40\,cm long gas cell placed in the beam path of the Aries 40\,m
radio telescope receivers operating in the 41-49 GHz frequency range interfaced
with fast Fourier transform spectrometers providing 2 GHz bandwidth and 38 kHz
resolution.
The impedance matching of the cell windows has been studied using different
materials. The choice of the material and its thickness was critical to obtain
a sensitivity identical to that of standard radio astronomical observations.
Spectroscopic signals arising from very low partial pressures of CH3OH,
CH3CH2OH, HCOOH, OCS,CS, SO2 (<1E-03 mbar) were detected in a few seconds. Fast
data acquisition was achieved allowing for kinetic measurements in
fragmentation experiments using electron impact or UV irradiation. Time
evolution of chemical reactions involving OCS, O2 and CS2 was also observed
demonstrating that reactive species, such as CS, can be maintained with high
abundance in the gas phase during these experiments.Comment: Accepted for publication in Astronomy and Astrophysics in September
21, 2017. 16 pages, 18 figure
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