Risk assessment in a materials recycling facility: Perspectives for reducing operational issues

Mechanical separation of light packaging waste is a useful practice for improving the quality of the recyclable waste flows and its exploitation in a frame of the circular economy. Materials Recovery Facilities can treat from 3000 to 5000 tons per year of light packaging waste. Concerning the plastic content, this is divided in four flows: PET, HDPE, other plastics, and waste rejects. The last two are generally used for energy recovery. For improving the quality of the recyclable plastic waste, a manual separation is required for reducing the impurities detectable in the final products. However, this practice could enhance the risk at work of the operators, which should be constantly monitored. This article explores the main differences of a manual separation and of a mechanical separation, assessing the costs and the health risk for the workers. The analysis started from the situation in an Italian Materials Recovery Facility, generalizing the context; a future scenario with the application of a mechanical separation is theoretically introduced. The main results obtained suggest that the manual separation plant improves the quality of the material, though increasing the risk of the operators due to the possible contact with sharp waste, sanitary danger, and risk of injuries for the mismanagement of machines, among others. The mechanical separation can be considered a real advantage from an economic point of view, since the operating costs are lower and the investment could be recovered in around 10 years, in an Italian-like context. On balance, on the one hand, the article provides indications for the private sector for improving the management of a Materials Recovery Facility, while, on the other hand, it detects the main pros and cons of both methodologies. © 2018 by the authors

The ortho-to-para ratio of ammonia in the L1157 outflow

We have measured the ortho-to-para ratio of ammonia in the blueshifted gas of the L1157 outflow by observing the six metastable inversion lines from (J, K) = (1, 1) to (6, 6). The highly excited (5, 5) and (6, 6) lines were first detected in the low-mass star forming regions. The rotational temperature derived from the ratio of four transition lines from (3, 3) to (6, 6) is 130-140 K, suggesting that the blueshifted gas is heated by a factor of ~10 as compared to the quiescent gas. The ortho-to-para ratio of the NH3 molecules in the blueshifted gas is estimated to be 1.3--1.7, which is higher than the statistical equilibrium value. This ratio provides us with evidence that the NH3 molecules have been evaporated from dust grains with the formation temperature between 18 and 25 K. It is most likely that the NH3 molecules on dust grains have been released into the gas phase through the passage of strong shock waves produced by the outflow. Such a scenario is supported by the fact that the ammonia abundance in the blueshifted gas is enhanced by a factor of ~5 with respect to the dense quiescent gas.Comment: 16 pages, including 3 PS figures. To appear in the ApJ (Letters). aastex macro

Search for LBV Candidates in the M33 Galaxy

A total of 185 luminous blue variable (LBV) candidates with V < 18.5 and B-V < 0.35 are selected based on the photometrical Survey of Local Group Galaxies made by P. Massey et al. 2006. The candidates were selected using aperture photometry of H-alpha images. The primary selection criterion is that the prospective candidate should be a blue star with H-aplha emission. In order not to miss appreciably reddened LBV candidates, we compose an additional list of 25 presumably reddened (0.35 < B-V < 1.2, V < 18.5) emission star candidates. A comparison with the list of known variables in the M33 galaxy showed 29% of our selected candidates to be photometrically variable. We also find our list to agree well with the lists of emission-line objects obtained in earlier papers using different methods.Comment: 6 figure

The symbiotic star CH Cygni – II. The ejecta from the 1998-2000 active phase

We present Hubble Space Telescope (HST) imaging, a Very Large Array (VLA) radio map (4.74 GHz), optical high-resolution (echelle) spectroscopy and UBV photoelectric photometry of the symbiotic star CH Cyg obtained during its 1998–2000 active phase. The HST imaging, taken during eclipse, shows the central stars are embedded in a nebula extending to 620 ± 150 au for a distance of 270 ± 66 pc. The inner nebula is strongly influenced by the onset of activity and associated outflow in 1998. The surface brightness contours of the contemporaneous radio VLA observation agree well with HST images. Photometric observations of the broad 1999 U-minimum suggest that it is due to the eclipse of the active hot component by the giant on the long-period (14.5 yr) outer orbit. We also find that the onset of the 1998 and the 1992 active periods occur at the same orbital phase of the inner binary. Spectroscopic observations reveal two types of outflow from the active star: a high-velocity (>1200 km s−1) hot star wind sporadically alternating with a more massive outflow indicated by P-Cygni-like profiles. We present evidence connecting the extended nebulosity with the high-velocity shocked outflow, and hence the activity in the central binary

A Catalogue of Optically Selected Cores

We present a new catalogue of 406 dense cores optically selected by using the STScI Digitized Sky Survey (DSS). In this catalogue 306 cores have neither an Embedded YSO (EYSO) nor a Pre-Main-Sequence (PMS) star, 94 cores have EYSOs (1 core has both an EYSO and a PMS star), and 6 cores have PMS star only. Our sample of dense cores in the catalogue is fairly complete within a category of northern Lynds class 5, 6 clouds, and southern Hartley et al. (1986)'s class A clouds, providing a database useful for the systematic study of dense cores. Most of the cores listed in the catalogue have diameters between $0.05 - 0.36$ pc with a mean of $\sim 0.24$ pc. The sizes ($\sim 0.33$ pc in the mean) of cores with EYSOs are found to be usually larger than the sizes ($\sim 0.22$ pc in the mean) of starless cores. The typical mean gas density of the cores is $\sim7\times 10^3 cm^{-3}$. Most of the cores are more likely elongated than spherical (mean aspect ratio: $\sim 2.4$). The ratio of the number of cores with EYSOs to the number of starless cores for our sample is about 0.3, suggesting that the typical lifetime of starless cores is $0.3-1.6$ Myr, about 3 times longer than the duration of the Class 0 and Class I phases. This lifetime is shorter than expected from models of ambipolar diffusion, by factors of 2-44.Comment: 22 pages, 8 figures, 3 tables, and to appear in ApJS. Harvard-Smithsonian Center for Astrophysic

Detection of Gamma-ray Emission from the Eta-Carinae Region

We present the results of extensive observations by the gamma-ray AGILE satellite of the Galactic region hosting the Carina nebula and the remarkable colliding wind binary Eta Carinae (Eta Car) during the period 2007 July to 2009 January. We detect a gamma-ray source (1AGL J1043-5931) consistent with the position of Eta Car. If 1AGL J1043-5931 is associated with the Eta Car system our data provide the long sought first detection above 100 MeV of a colliding wind binary. The average gamma-ray flux above 100 MeV and integrated over the pre-periastron period 2007 July to 2008 October is F = (37 +/- 5) x 10-8 ph cm-2 s-1 corresponding to an average gamma-ray luminosity of L = 3.4 x 10^34 erg s-1 for a distance of 2.3 kpc. We also report a 2-day gamma-ray flaring episode of 1AGL J1043-5931 on 2008 Oct. 11-13 possibly related to a transient acceleration and radiation episode of the strongly variable shock in the system.Comment: 5 pages, 4 figure, accepted for publication in ApJ Letter

Digitatio and Scientific Exploitation of the Italian and Vatican Astronomical Plate Archives

There is a widespread interest to digitize the precious information contained in the astronomical plate archives, both for the preservation of their content and for its fast distribution to all interested researchers in order to achieve their better scientific exploitation. This paper presents the first results of our large-scale project to digitize the archive of plates of the Italian Astronomical Observatories and of the Specola Vaticana. Similar systems, composed by commercial flat-bed retro-illuminated scanners plus dedicated personal computers and acquisition and analysis software, have been installed in all participating Institutes. Ad-hoc codes have been developed to acquire the data, to test the suitability of the machines to our scientific needs, and to reduce the digital data in order to extract the astrometric, photometric and spectroscopic content. Two more elements complete the overall project: the provision of high quality BVRI CCD sequences in selected fields with the Campo Imperatore telescopes, and the distribution of the digitized information to all interested researchers via the Web. The methods we have derived in the course of this project have been already applied successfully to plates taken by other Observatories, for instance at Byurakan and at Hamburg.Comment: To appear in Experimental Astronom

The CHESS chemical Herschel surveys of star forming regions: Peering into the protostellar shock L1157-B1. I. Shock chemical complexity

We present the first results of the unbiased survey of the L1157-B1 bow shock, obtained with HIFI in the framework of the key program Chemical Herschel surveys of star forming regions (CHESS). The L1157 outflow is driven by a low-mass Class 0 protostar and is considered the prototype of the so-called chemically active outflows. The bright blue-shifted bow shock B1 is the ideal laboratory for studying the link between the hot (around 1000-2000 K) component traced by H2 IR-emission and the cold (around 10-20 K) swept-up material. The main aim is to trace the warm gas chemically enriched by the passage of a shock and to infer the excitation conditions in L1157-B1. A total of 27 lines are identified in the 555-636 GHz region, down to an average 3 sigma level of 30 mK. The emission is dominated by CO(5-4) and H2O(110-101) transitions, as discussed by Lefloch et al. (2010). Here we report on the identification of lines from NH3, H2CO, CH3OH, CS, HCN, and HCO+. The comparison between the profiles produced by molecules released from dust mantles (NH3, H2CO, CH3OH) and that of H2O is consistent with a scenario in which water is also formed in the gas-phase in high-temperature regions where sputtering or grain-grain collisions are not efficient. The high excitation range of the observed tracers allows us to infer, for the first time for these species, the existence of a warm (> 200 K) gas component coexisting in the B1 bow structure with the cold and hot gas detected from ground

CHESS, Chemical Herschel surveys of star forming regions:Peering into the protostellar shock L1157-B1

The outflow driven by the low-mass class 0 protostar L1157 is the prototype of the so-called chemically active outflows. The bright bowshock B1 in the southern outflow lobe is a privileged testbed of magneto-hydrodynamical (MHD) shock models, for which dynamical and chemical processes are strongly interdependent. We present the first results of the unbiased spectral survey of the L1157-B1 bowshock, obtained in the framework of the key program "Chemical Herschel Surveys of Star Forming Regions" (CHESS). The main aim is to trace the warm and chemically enriched gas and to infer the excitation conditions in the shock region. The CO 5-4 and H2O lines have been detected at high-spectral resolution in the unbiased spectral survey of the HIFI-Band 1b spectral window (555-636 GHz), presented by Codella et al. in this volume. Complementary ground-based observations in the submm window help establish the origin of the emission detected in the main-beam of HIFI, and the physical conditions in the shock.}{Both lines exhibit broad wings, which extend to velocities much higher than reported up to now. We find that the molecular emission arises from two regions with distinct physical conditions: an extended, warm (100K), dense (3e5 cm-3) component at low-velocity, which dominates the water line flux in Band~1; a secondary component in a small region of B1 (a few arcsec) associated with high-velocity, hot (> 400 K) gas of moderate density ((1.0-3.0)e4 cm-3), which appears to dominate the flux of the water line at 179mu observed with PACS. The water abundance is enhanced by two orders of magnitude between the low- and the high-velocity component, from 8e-7 up to 8e-5. The properties of the high-velocity component agree well with the predictions of steady-state C-shock models.Comment: Accepted for Publication in Astronomy and Astrophysics (Herschel Special Issue