22 research outputs found
Single and Double Photoionization and Photodissociation of Toluene by Soft X-rays in Circumstellar Environment
The formation of polycyclic aromatic hydrocarbons (PAHs) and their methyl
derivatives occurs mainly in the dust shells of asymptotic giant branch (AGB)
stars. The bands at 3.3 and 3.4 m, observed in infrared emission spectra
of several objects, are attributed C-H vibrational modes in aromatic and
aliphatic structures, respectively. In general, the feature at 3.3 m is
more intense than the 3.4 m. Photoionization and photodissociation
processes of toluene, the precursor of methylated PAHs, were studied using
synchrotron radiation at soft X-ray energies around the carbon K edge with
time-of-flight mass spectrometry. Partial ion yields of a large number of ionic
fragments were extracted from single and 2D-spectra, where electron-ion
coincidences have revealed the doubly charged parent-molecule and several
doubly charged fragments containing seven carbon atoms with considerable
abundance. \textit{Ab initio} calculations based on density functional theory
were performed to elucidate the chemical structure of these stable dicationic
species. The survival of the dications subjected to hard inner shell ionization
suggests that they could be observed in the interstellar medium, especially in
regions where PAHs are detected. The ionization and destruction of toluene
induced by X-rays were examined in the T Dra conditions, a carbon-rich AGB
star. In this context, a minimum photodissociation radius and the half-life of
toluene subjected to the incidence of the soft X-ray flux emitted from a
companion white dwarf star were determined.Comment: 11 pages, 4 figures, accept for publication in Ap
Time needed to intubate and suction a manikin prior to instituting positive pressure ventilation: a simulation trial
Tracheal suctioning in non-vigorous newborn delivered through meconium-stained amniotic fluid (MSAF) is supposed to delay initiation of positive pressure ventilation (PPV), but the magnitude of such delay is unknown. To compare the time of PPV initiation when performing immediate laryngoscopy with intubation and suctioning vs. performing immediate PPV without intubation in a manikin model. Randomized controlled crossover (AB/BA) trial comparing PPV initiation with or without endotracheal suctioning in a manikin model of non-vigorous neonates born through MSAF. Participants were 20 neonatologists and 20 pediatric residents trained in advanced airway management. Timing of PPV initiation was longer with vs. without endotracheal suctioning in both pediatric residents (mean difference 13\ua0s, 95% confidence interval 8 to 18\ua0s; p\ua0< 0.0001) and neonatologists (mean difference 12\ua0s, 95% confidence interval 8 to 16\ua0s; p < 0.0001). The difference in timing of PPV initiation was similar between pediatric residents and neonatologists (mean difference 12 1\ua0s, 95% confidence interval 12 7 to 6\ua0s; p\ua0= 0.85). Conclusions: Performing immediate laryngoscopy with intubation and suctioning was associated with longer\u2014but not clinically relevant\u2014time of initiation of PPV compared with immediate PPV without intubation in a manikin model. While suggesting negligible delay in starting PPV, further studies in a clinical setting are warranted. Registration: clinicaltrial.gov NCT04076189.What is Known:\u2022 Management of the non-vigorous newborn delivered through meconium-stained amniotic fluid remains still controversial.\u2022 Tracheal suctioning in non-vigorous newborn delivered through meconium-stained amniotic fluid is supposed to delay initiation of positive pressure ventilation, but the magnitude of such delay is unknown.What is New:\u2022 Performing immediate ventilation without intubation was associated with shorter\u2014but not clinically relevant\u2014time of initiation of ventilation compared to immediate laryngoscopy with intubation and suctioning in a manikin model.\u2022 Further studies in a clinical setting are warranted
Dispersed generation to provide ancillary services: AlpStore project
In the future, electrical systems should be
able to integrate all users at the same time and
guarantee power quality, stability and safety over
time. The integration of renewable energy sources
leads to new issues involving the intermittence of this
generation typology. A high penetration of
intermittent power plants will reduce the capability of
the system to overcome critical events (e.g. frequency
oscillations and voltage profile perturbation). This
work presents new regulation schemes/functions
developed in the AlpStore project framework, devoted
to managing dispersed generation in order to provide
ancillary services to the main grid. The work
developed can be split into two main items: reactive
injection regulation and frequency control regulation.
The first regulation is devoted to increasing the
Hosting Capacity of the distribution grid (i.e. it results
to be a local control), whereas the latter aims to
guarantee the energy balance of the national electric
grid (i.e. it could be classified as a grid control)