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1.
Astron Astrophys ; 6472021 Mar.
Article in English | MEDLINE | ID: mdl-33850332

ABSTRACT

We present the discovery in TMC-1 of allenyl acetylene, H2CCCHCCH, through the observation of nineteen lines with a signal-to-noise ratio ~4-15. For this species, we derived a rotational temperature of 7±1K and a column density of 1.2±0.2×1013 cm-2. The other well known isomer of this molecule, methyl diacetylene (CH3C4H), has also been observed and we derived a similar rotational temperature, Tr=7.0±0.3 K, and a column density for its two states (A and E) of 6.5±0.3×1012 cm-2. Hence, allenyl acetylene and methyl diacetylene have a similar abundance. Remarkably, their abundances are close to that of vinyl acetylene (CH2CHCCH). We also searched for the other isomer of C5H4, HCCCH2CCH (1.4-Pentadiyne), but only a3σ upper limit of 2.5×1012 cm-2 to the column density can be established. These results have been compared to state-of-the-art chemical models for TMC-1, indicating the important role of these hydrocarbons in its chemistry. The rotational parameters of allenyl acetylene have been improved by fitting the existing laboratory data together with the frequencies of the transitions observed in TMC-1.

2.
Astron Astrophys ; 6482021 Apr.
Article in English | MEDLINE | ID: mdl-33850333

ABSTRACT

We report the detection of the sulfur-bearing species NCS, HCCS, H2CCS, H2CCCS, and C4S for the first time in space. These molecules were found towards TMC-1 through the observation of several lines for each species. We also report the detection of C5S for the first time in a cold cloud through the observation of five lines in the 31-50 GHz range. The derived column densities are N(NCS) = (7.8±0.6)×1011 cm-2, N(HCCS) = (6.8±0.6)×1011 cm-2, N(H2CCS) = (7.8±0.8)×1011 cm-2, N(H2CCCS) = (3.7±0.4)×1011 cm-2, N(C4S) = (3.8±0.4)×1010 cm-2, and N(C5S) = (5.0±1.0)×1010 cm-2. The observed abundance ratio between C3S and C4S is 340, that is to say a factor of approximately one hundred larger than the corresponding value for CCS and C3S. The observational results are compared with a state-of-the-art chemical model, which is only partially successful in reproducing the observed abundances. These detections underline the need to improve chemical networks dealing with S-bearing species.

3.
Astron Astrophys ; 6472021 Mar.
Article in English | MEDLINE | ID: mdl-33833468

ABSTRACT

We present the discovery in TMC-1 of vinyl acetylene, CH2CHCCH, and the detection, for the first time in a cold dark cloud, of HCCN, HC4N, and CH3CH2CN. A tentative detection of CH3CH2CCH is also reported. The column density of vinyl acetylene is (1.2±0.2)×1013 cm-2, which makes it one of the most abundant closed-shell hydrocarbons detected in TMC-1. Its abundance is only three times lower than that of propylene, CH3CHCH2. The column densities derived for HCCN and HC4N are (4.4±0.4)×1011 cm-2 and (3.7±0.4)×1011 cm-2, respectively. Hence, the HCCN/HC4N abundance ratio is 1.2±0.3. For ethyl cyanide we derive a column density of (1.1 ±0.3)×1011 cm-2. These results are compared with a state-of-the-art chemical model of TMC-1, which is able to account for the observed abundances of these molecules through gas-phase chemical routes.

4.
Astron Astrophys ; 6452021 Jan.
Article in English | MEDLINE | ID: mdl-33408420

ABSTRACT

CONTEXT: Yebes 40m radio telescope is the main and largest observing instrument at Yebes Observatory and it is devoted to Very Long Baseline Interferometry (VLBI) and single dish observations since 2010. It has been covering frequency bands between 2 GHz and 90 GHz in discontinuous and narrow windows in most of the cases, to match the current needs of the European VLBI Network (EVN) and the Global Millimeter VLBI Array (GMVA). AIMS: Nanocosmos project, a European Union funded synergy grant, opened the possibility to increase the instantaneous frequency coverage to observe many molecular transitions with single tunnings in single dish mode. This reduces the observing time and maximises the output from the telescope. METHODS: We present the technical specifications of the recently installed 31.5 - 50GHz (Q band) and 72 - 90.5 GHz (W band) receivers along with the main characteristics of the telescope at these frequency ranges. We have observed IRC+10216, CRL 2688 and CRL 618, which harbour a rich molecular chemistry, to demonstrate the capabilities of the new instrumentation for spectral observations in single dish mode. RESULTS: The results show the high sensitivity of the telescope in the Q band. The spectrum of IRC+10126 offers a signal to noise ratio never seen before for this source in this band. On the other hand, the spectrum normalised by the continuum flux towards CRL 618 in the W band demonstrates that the 40 m radio telescope produces comparable results to those from the IRAM 30 m radio telescope, although with a smaller sensitivity. The new receivers fulfil one of the main goals of Nanocosmos and open the possibility to study the spectrum of different astrophysical media with unprecedented sensitivity.

5.
Astron Astrophys ; 6302019 Oct.
Article in English | MEDLINE | ID: mdl-31579315

ABSTRACT

We report on the detection of two series of harmonically related doublets in IRC +10216. From the observed frequencies, the rotational constant of the first series is B = 1380.888 MHz and that of the second series is B = 1381.512 MHz. The two series correspond to two species with a 2Σ electronic ground state. After considering all possible candidates, and based on quantum chemical calculations, the first series is assigned to MgC3N and the second to MgC4H. For the latter species, optical spectroscopy measurements support its identification. Unlike diatomic metal-containing molecules, the line profiles of the two new molecules indicate that they are formed in the outer layers of the envelope, as occurs for MgNC and other polyatomic metal-cyanides. We also confirm the detection of MgCCH that was previously reported from the observation of two doublets. The relative abundance of MgC3N with respect to MgNC is close to one while that of MgC4H relative to MgCCH is about ten. The synthesis of these magnesium cyanides and acetylides in IRC +10216 can be explained in terms of a two-step process initiated by the radiative association of Mg+ with large cyanopolyynes and polyynes followed by the dissociative recombination of the ionic complexes.

6.
Article in English | MEDLINE | ID: mdl-31186577

ABSTRACT

We present a new experimental setup devoted to the study of gas phase molecules and processes using broad band high spectral resolution rotational spectroscopy. A reactor chamber has been equipped with radio receivers similar to those used by radio astronomers to search for molecular emission in space. The whole Q (31.5-50 GHz) and W bands (72-116.5 GHz) are available for rotational spectroscopy observations. The receivers are equipped with 16×2.5 GHz Fast Fourier Transform spectrometers with a spectral resolution of 38.14 kHz allowing the simultaneous observation of the complete Q band and one third of the W band. The whole W band can be observed in three settings in which the Q band is always observed. Species such as CH3CN, OCS, and SO2 are detected, together with many of their isotopologues and vibrationally excited states, in very short observing times. The system permits automatic overnight observations and integration times as long as 2.4×105 seconds have been reached. The chamber is equipped with a radiofrequency source to produce cold plasmas and with four ultraviolet lamps to study photochemical processes. Plasmas of CH4, N2, CH3CN, NH3, O2, and H2, among other species, have been generated and the molecular products easily identified by their rotational spectrum, and mass spectrometry and optical spectroscopy. Finally, the rotational spectrum of the lowest energy conformer of CH3CH2NHCHO (N-Ethylformamide), a molecule previously characterized in microwave rotational spectroscopy, has been measured up to 116.5 GHz allowing the accurate determination of its rotational and distortion constants and its search in space.

7.
Astron Astrophys ; 6092018 Jan.
Article in English | MEDLINE | ID: mdl-29277841

ABSTRACT

We present a proof of concept on the coupling of radio astronomical receivers and spectrometers with chemical reactors and 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 (<10-3 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.

8.
Astron Astrophys ; 5792015 Jul 01.
Article in English | MEDLINE | ID: mdl-26543239

ABSTRACT

Cyanogen (NCCN) is the simplest member of the series of dicyanopolyynes. It has been hypothesized that this family of molecules can be important constituents of interstellar and circumstellar media, although the lack of a permanent electric dipole moment prevents its detection through radioastronomical techniques. Here we present the first solid evidence of the presence of cyanogen in interstellar clouds through the detection of its protonated form toward the cold dark clouds TMC-1 and L483. Protonated cyanogen (NCCNH+) has been identified through the J = 5 - 4 and J = 10 - 9 rotational transitions using the 40m radiotelescope of Yebes and the IRAM 30m telescope. We derive beam averaged column densities for NCCNH+ of (8.6 ± 4.4) × 1010 cm-2 in TMC-1 and (3.9 ± 1.8) × 1010 cm-2 in L483, which translate to fairly low fractional abundances relative to H2, in the range (1-10) × 10-12. The chemistry of protonated molecules in dark clouds is discussed, and it is found that, in general terms, the abundance ratio between the protonated and non protonated forms of a molecule increases with increasing proton affinity. Our chemical model predicts an abundance ratio NCCNH+/NCCN of ~ 10-4, which implies that the abundance of cyanogen in dark clouds could be as high as (1-10) × 10-8 relative to H2, i.e., comparable to that of other abundant nitriles such as HCN, HNC, and HC3N.

9.
Plant Dis ; 93(2): 180-184, 2009 Feb.
Article in English | MEDLINE | ID: mdl-30764107

ABSTRACT

In total, 140 populations of the genus Meloidogyne collected from representative horticultural regions of Spain and maintained at the Department of Agroecology, Institute of Agrarian Sciences, Madrid were characterized using perineal morphology, sequenced characterized amplified region polymerase chain reaction with species-specific primers, and bioassay. Using a modified North Carolina differential host test as a basis, 13 Meloidogyne populations did not fit into the published race scheme. These populations had very limited host ranges, reproducing only on susceptible tomato cv. Marmande and sometimes also on tobacco cv. NC95 and the pepper cv. Sonar in the case of Meloidogyne arenaria. They did not reproduce on cotton or peanut. The species and new races were identified as M. incognita races 5 (6 populations) and 6 (2 populations) and M. javanica race 5 (2 populations), with new records of M. arenaria race 3 (2 populations) and M. javanica race 1 (23 populations) for Spain.

10.
Arch. Fac. Med. Zaragoza ; 41(2): 52-54, ago. 2001. tab, ilus
Article in Es | IBECS | ID: ibc-22974

ABSTRACT

La hipercalciuria idiopática es un cuadro clínico frecuente que a nuestro parecer podría estar infradiagnosticado dada su clínica tan inespecífica y la escasa literatura existente sobre el mismo. Para su diagnóstico se requiere pruebas complementarias accesibles al médico de Atención Primaria por lo que debería ser a este nivel desde donde se diagnosticaran la mayor parte de estos casos (AU)


Subject(s)
Female , Male , Child , Humans , Calcium/urine , Primary Health Care , Urologic Diseases/diagnosis
11.
Arch. Fac. Med. Zaragoza ; 41(1): 21-22, abr. 2001.
Article in Es | IBECS | ID: ibc-22968

ABSTRACT

Se describe el caso de un paciente con enfermedad de Charcot-Marie-Tooth con la rara asociación a un trastorno de la conducción cardíaca sin miocardiopatía dilatada al que se consideró candidato para cardioversión eléctrica con mala respuesta a la misma. Se revisa la literatura de los casos descritos con esta asociación y se aporta la novedad del mal resultado obtenido con la cardioversión lo cual puede contribuir a un mejor conocimiento de los trastornos de la conducción cardíaca asociados a esta enfermedad (AU)


Subject(s)
Adult , Humans , Arrhythmias, Cardiac/complications , Charcot-Marie-Tooth Disease/diagnosis , Charcot-Marie-Tooth Disease/complications
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