25 research outputs found
Morganella morganii septicemia and concurrent renal crassicaudiasis in a Cuvier’s beaked whale (Ziphius cavirostris) stranded in Italy
Information regarding bacterial diseases in Cuvier's beaked whale (CBW, Ziphius cavirostris) is scattered and mostly incomplete. This report describes a case of septicemia by Morganella morganii in a juvenile male CBW with concurrent renal crassicaudiasis. The animal stranded along the Ligurian coastline (Italy) and underwent a systematic post-mortem examination to determine the cause of death. Histopathology showed lesions consistent with a septicemic infection, severe meningoencephalitis, and renal crassicaudiasis. An M. morganii alpha-hemolytic strain was isolated in pure culture from liver, lung, prescapular lymph node, spleen, hepatic and renal abscesses, and central nervous system (CNS). The antimicrobial susceptibility profile of the strain was evaluated with the minimum inhibitory concentrations (MICs) method and reduced susceptibility to Trimethoprim-Sulfamethoxazole is reported. Crassicauda sp. nematodes were retrieved from both kidneys. No other pathogens were detected by immunohistochemistry, serology, or biomolecular analyses. Toxicological investigations detected high concentrations of immunosuppressant pollutants in the blubber. The chronic parasitic infestation and the toxic effects of xenobiotics likely compromised the animal's health, predisposing it to an opportunistic bacterial infection. To our knowledge, this is the first description of M. morganii septicemia with CNS involvement in a wild cetacean
PAH chemistry and IR emission from circumstellar disks
Aims. The chemistry of, and infrared (IR) emission from, polycyclic aromatic
hydrocarbons (PAHs) in disks around Herbig Ae/Be and T Tauri stars are
investigated. The equilibrium distribution of the PAHs over all accessible
charge/hydrogenation states depends on the size and shape of the PAHs and on
the physical properties of the star and surrounding disk.
Methods. A chemistry model is created to calculate this equilibrium
distribution. Destruction of PAHs by ultraviolet (UV) photons, possibly in
multi-photon absorption events, is taken into account. The chemistry model is
coupled to a radiative transfer code to provide the physical parameters and to
combine the PAH emission with the spectral energy distribution (SED) from the
star+disk system.
Results. Normally hydrogenated PAHs in Herbig Ae/Be disks account for most of
the observed PAH emission, with neutral and positively ionized species
contributing in roughly equal amounts. Close to the midplane, the PAHs are more
strongly hydrogenated and negatively ionized, but these species do not
contribute to the overall emission because of the low UV/optical flux deep
inside the disk. PAHs of 50 carbon atoms are destroyed out to 100 AU in the
disk's surface layer, and the resulting spatial extent of the emission does not
agree well with observations. Rather, PAHs of about 100 carbon atoms or more
are predicted to cause most of the observed emission. The emission is extended
on a scale similar to that of the size of the disk. Furthermore, the emission
from T Tauri disks is much weaker and concentrated more towards the central
star than that from Herbig Ae/Be disks. Positively ionized PAHs are predicted
to be largely absent in T Tauri disks because of the weaker radiation field.Comment: 13 pages, 8 figures, accepted for publication in A&
Spitzer-IRS spectra of disks around T Tauri stars II. PAH emission features
Aims: We search for PAH features towards T Tauri stars and compare them with
surveys of Herbig Ae/Be stars. The presence and strength of the PAH features
are interpreted with disk radiative transfer models exploring the PAH feature
dependence on the incident UV radiation, PAH abundance and disk parameters.
Methods: Spitzer Space Telescope 5-35 micron spectra of 54 pre-main sequence
stars with disks were obtained, consisting of 38 T Tauri, 7 Herbig Ae/Be and 9
stars with unknown spectral type.
Results: Compact PAH emission is detected towards at least 8 sources of which
5 are Herbig Ae/Be stars. The 11.2 micron PAH feature is detected in all of
these sources, as is the 6.2 micron PAH feature where short wavelength data are
available. However, the 7.7 and 8.6 micron features appear strongly in only 1
of these 4 sources. PAH emission is observed towards at least 3 T Tauri stars
(8% detection rate). The lowest mass source with PAHs in our sample is T Cha
(G8). All 4 sources in our sample with evidence for dust holes in their inner
disk show PAH emission, increasing the feature/continuum ratio. Typical 11.2
micron line intensities are an order of magnitude lower than those observed for
the more massive Herbig Ae/Be stars. Measured line fluxes indicate PAH
abundances that are factors of 10-100 lower than standard interstellar values.
Conversely, PAH features from disks exposed to stars with Teff<=4200K without
enhanced UV are predicted to be below the current detection limit, even for
high PAH abundances. Disk modeling shows that the 6.2 and 11.2 micron features
are the best PAH tracers for T Tauri stars, whereas the 7.7 and 8.6 micron
bands have low feature over continuum ratios due to the strongly rising
silicate emission.Comment: 20 pages, 15 figures, accepted for publication in A&
Interstellar Grains -- The 75th Anniversary
The year of 2005 marks the 75th anniversary since Trumpler (1930) provided
the first definitive proof of interstellar grains by demonstrating the
existence of general absorption and reddening of starlight in the galactic
plane. This article reviews our progressive understanding of the nature of
interstellar dust.Comment: invited review article for the "Light, Dust and Chemical Evolution"
conference (Gerace, Italy, 26--30 September 2004), edited by F. Borghese and
R. Saija, 2005, in pres
Space as a Tool for Astrobiology: Review and Recommendations for Experimentations in Earth Orbit and Beyond
Progetto neutronico preliminare di un dispositivo per boroterapia basato su un acceleratore di protoni
Enantioselective hydrogenation of ethyl pyruvate in biphasic liquid–liquid media by reusable surfactant-stabilized aqueous suspensions of platinum nanoparticles
International audienceAqueous suspensions of modified cinchonidine platinum nanoparticles produced from H2PtCl6 reduction in the presence of the surfactant N,N-dimethyl-N-cetyl-N-(2-hydroxyethyl)ammonium chloride salt have shown efficient activity for the asymmetric hydrogenation of ethyl pyruvate in biphasic media under hydrogen pressure. The aqueous phase containing the Pt(0) nanocatalysts can be used for further runs with a total conservation of activity and enantioselectivity for (R)-(+)-ethyl lactate up to 55%. Characterization of the reusable catalytic system by transmission electron microscopy revealed the formation of a “colloidal superstructur