Protonated CO2 in massive star-forming clumps

Interstellar CO2 is an important reservoir of carbon and oxygen, and one of the major constituents of the icy mantles of dust grains, but it is not observable directly in the cold gas because has no permanent dipole moment. Its protonated form, HOCO+, is believed to be a good proxy for gaseous CO2. However, it has been detected in only a few star-forming regions so far, so that its interstellar chemistry is not well understood. We present new detections of HOCO+ lines in 11 high-mass star-forming clumps. Our observations increase by more than three times the number of detections in star-forming regions so far. We have derived beam-averaged abundances relative to H2 in between 0.3 and 3.8 x 10^{-11}. We have compared these values with the abundances of H13CO+, a possible gas-phase precursor of HOCO+, and CH3OH, a product of surface chemistry. We have found a positive correlation with H13CO+, while with CH3OH there is no correlation. We suggest that the gas-phase formation route starting from HCO+ plays an important role in the formation of HOCO+, perhaps more relevant than protonation of CO2 (upon evaporation of this latter from icy dust mantles).Comment: 5 pages, 4 figures, 1 table, accepted for publication in MNRA

Effects of Wood Distillate (Pyroligneous Acid) on the Yield Parameters and Mineral Composition of Three Leguminous Crops

The excessive use of chemical fertilizers and pesticides in agriculture is increasing the demand for novel products to improve the quality of crops in a more sustainable way. Wood distillate (WD, pyroligneous acid) is a by-product obtained during the pyrolysis of plant biomass that can be successfully applied in agriculture due to its ability to enhance the growth, size, and weight of edible plant parts. However, there is little information concerning its plant yield-promoting effects on leguminous crops. The present work investigated the effects of WD on the yield, protein content and mineral composition of chickpea (Cicer arietinum L.), lentil (Lens culinaris L.) and bean (Phaseolus vulgaris L.) plants grown in field conditions. The application of WD showed remarkable yield-promoting effects mostly in lentil plants, which significantly increased plant and shoot biomass, the number and weight of both pods and seeds, as well as the total seed protein content. Furthermore, seeds from WD-treated plants differentially increased the concentration of elements with high nutritional value for human health, including Fe, Ca, Mg and K. These results suggest that the effects of WD among the legumes tested are species-specific and that WD could be an optimal candidate to grow high-yielding legumes with improved seed nutritional quality

PREVALENCE OF BYOGENES AMMINS IN SEASONED D.O.P. CHEESE TOSCANO PECORINO

Pecorino cheese is one of the “D.O.P.” products made in Tuscany. There are two types of pecorino cheese one of which undergoes a curing time period which is not less than four months. Considering this curing time period, processes are conceivable that could lead to the formation of amines such as free amino acids. The biogenic amines have unquestionable effects on health in particular histamine and tyramine, they are also important indicators of hygienic quality of the profile of the movement shortly after the curing time period and included in the shelf life period which the product is commercialized

The GUAPOS project: III. Characterization of the O- and N-bearing complex organic molecules content and search for chemical differentiation

Context. The G31.41+0.31 Unbiased ALMA sPectral Observational Survey (GUAPOS) project targets the hot molecular core (HMC) G31.41+0.31 (G31) to reveal the complex chemistry of one of the most chemically rich high-mass star-forming regions outside the Galactic center (GC). Aims. In the third paper of the project we present a study of nine O-bearing (CH3OH, 13CH3OH, CH318OH, CH3CHO, CH3OCH3, CH3COCH3, C2H5OH, aGg′-(CH2OH)2, and gGg′-(CH2OH)2) and six N-bearing (CH3CN,13CH3CN, CH313CN, C2H3CN, C2H5CN, and C2H513CN) complex organic molecules toward G31. The aim of this work is to characterize the abundances in G31 and to compare them with the values estimated in other sources. Moreover, we searched for a possible chemical segregation between O-bearing and N-bearing species in G31, which hosts four compact sources as seen with higher angular resolution data. In the discussion we also include the three isomers of C2H4O2 and the O- and N-bearing molecular species NH2CHO, CH3NCO, CH3C(O)CH2, and CH3NHCHO, which were analyzed in previous GUAPOS papers. Methods. Observations were carried out with the interferometer ALMA and cover the entire Band 3 from 84 to 116 GHz (∼32 GHz bandwidth) with an angular resolution of 1.2″ × 1.2″ (∼4400 au × 4400 au) and a spectral resolution of ∼0.488 MHz (∼1.3- 1.7 km s-1). The transitions of the 14 molecular species were analyzed with the tool SLIM of MADCUBA to determine the physical parameters of the emitting gas. Moreover, we analyzed the morphology of the emission of the molecular species. Results. The values of abundances with respect to H2 in G31 range from 10-6 to 10-10 for the different species. We compared the abundances with respect to methanol of O-bearing, N-bearing, and O- and N-bearing COMs in G31 with 27 other sources, including other hot molecular cores inside and outside the GC, hot corinos, shocked regions, envelopes around young stellar objects, and quiescent molecular clouds, and with chemical models. Conclusions. From the comparison with other sources there is not a unique template for the abundances in hot molecular cores, pointing toward the importance of the thermal history for the chemistry of the various sources. The abundances derived from the chemical models are in good agreement, within a factor of 10, with those of G31. From the analysis of the maps we derived the peak positions of all the molecular species toward G31. Different species peak at slightly different positions, and this, together with the different central velocities of the lines obtained from the spectral fitting, point to chemical differentiation of selected O-bearing species

Amides inventory towards the G+0.693-0.027 molecular cloud

Interstellar amides have attracted significant attentions as they are potential precursors for a wide variety of organics essential to life. However, our current understanding of their formation in space is heavily based on observations in star-forming regions and hence the chemical networks lack the constraints on their early origin. In this work, unbiased sensitive spectral surveys with IRAM 30m and Yebes 40m telescopes are used to systematically study a number of amides towards a quiescent Galactic Centre molecular cloud, G+0.693-0.027. We report the first detection of acetamide (CH3C(O)NH2) and trans-N-methylformamide (CH3NHCHO) towards this cloud. In addition, with the wider frequency coverage of the survey, we revisited the detection of formamide (NH2CHO) and urea (carbamide; NH2C(O)NH2), which had been reported previously towards G+0.693-0.027. Our results are compared with those present in the literature including recent laboratory experiments and chemical models. We find constant abundance ratios independently of the evolutionary stages, suggesting that amides related chemistry is triggered in early evolutionary stages of molecular cloud and remain unaffected by the warm-up phase during the star formation process. Although a correlation between more complex amides and NH2CHO have been suggested, alternative formation routes involving other precursors such as acetaldehyde (CH3CHO), methyl isocyanate (CH3NCO) and methylamine (CH3NH2) may also contribute to the production of amides. Observations of amides together with these species towards a larger sample of sources can help to constrain the amide chemistry in the interstellar medium.Comment: 16 pages, 8 figures, 3 tables, accepted for publication in Monthly Notices of the Royal Astronomical Societ

The first detection of SiC2_2 in the interstellar medium

We report the first detection of SiC$_2$ in the interstellar medium. The molecule was identified through six rotational transitions toward G\,+0.693$-$0.027, a molecular cloud located in the Galactic center. The detection is based on a line survey carried out with the GBT, the Yebes 40m, and the IRAM 30m telescopes covering a range of frequencies from 12 to 276 GHz. We fit the observed spectra assuming local thermodynamic equilibrium and derive a column density of ($1.02\pm0.04)\times10^{13}$ cm$^{-2}$, which gives a fractional abundance of $7.5\times10^{-11}$ with respect to H$_2$, and an excitation temperature of $5.9\pm0.2$ K. We conclude that SiC$_2$ can be formed in the shocked gas by a reaction between the sputtered atomic silicon and C$_2$H$_2$, or it can be released directly from the dust grains due to disruption. We also search for other Si-bearing molecules and detect eight rotational transitions of SiS and four transitions of Si$^{18}$O. The derived fractional abundances are $3.9\times10^{-10}$ and $2.1\times10^{-11}$, respectively. All Si-bearing species toward G\,+0.693$-$0.027 show fractional abundances well below what is typically found in late-type evolved stars.Comment: 8 pages, 5 figure