On the prospective detection of polyoxymethylene in comet 67P/Churyumov–Gerasimenko with the COSIMA instrument onboard Rosetta

The presence of polyoxymethylene (POM) in cometary grains has been debated years ago. Although never proven, its presence can not be excluded. Rosetta, the ESA mission to comet 67P/Churyumov–Gerasimenko, may answer this question. On board the spacecraft, COSIMA (COmetary Secondary Ion Mass Analyzer) will analyze the grains ejected from the nucleus using a Time Of Flight Secondary Ion Mass Spectrometer (TOF-SIMS). In this paper we report the extent to which COSIMA will be able to detect POM if this compound is present on cometary grains. We have analyzed two kinds of POM polymers with a laboratory model of COSIMA. Positive mass spectra display alternating sequence of peaks with a separation of 30.011 Da between 1 and 600 Da related to formaldehyde and its oligomers but also to the fragmentation of these oligomers. The separation of 30.011 Da of numbers peaks, corresponding to the fragmentation into H2CO is characteristic of POM and we show that it could be highlight by mathematical treatment. POM lifetime on COSIMA targets have also been studied as POM is thermally instable. It can be concluded that the cometary grains analysis have to be planned not too long after their collection in order to maximize the chances to detect POM. This work was supported by the Centre National d'Etudes Spatiales (CNES).

Primary productivity and mass fluxes for four stations in teh equatorial Pacific (Table 1)

Primary productivity (14C) and mass flux measurements using a free-drifting sediment trap deployed at 900 m were made at four stations in the Pacific Ocean between 12°N and 6°S at 153°W. The latitudinal variations in productivity were consistent with historical patterns showing the equator as a zone of high production and the oligotrophic waters north of the equatorial region as an area of low productivity. The correlation coefficient between the two sets of independent measurements was 0.999, indicating that in this oceanic area the activity of the primary producers was closely related to the total mass flux. A re-examination of historical data suggests that the downward flux of particulate organic carbon varies in direct proportion to the quotient of surface primary production raised to the 1.4 power and depth raised to the 0.63 power.

Cantos de Leopardi,

Translator's name, Calixto Oyuela, at head of title.

Del riparo de' pennelli alle rive del Po di Cremona : a sua eccellenza il signor marchese don Angiolo Luigi Maraviglia Mantegazza, consigliere intimo attuale di stato delle Ll. maestáa imperiali, e presidente della regia camera ec.

Acquisition made accessible thanks to a 2015-2017 grant from the Council on Libraries and Information Resources.

Frusta musicale, ossia, Lettere sugli abusi introdotti nella musica / Nicolò Eustachio Cattaneo.

Mode of access: Internet.

Romana antiquitas dissertationibus historico-criticis illustrata : quibus prisci scriptores emendati dilucidatique, recentes castigati inque meliorem ordinem digesti, veteres opiniones nouis fulcris firmatae, propria demum cogitata non infirmis coniecturis stabilita /

Signatures: a⁶ chi² A-2E⁸.

Integral equations

Mode of access: Internet.

Numismatica di Lipara /

Contains bibliographical references.