Deriving the extinction to young stellar objects using [FeII] near-infrared emission lines. Prescriptions from GIANO high-resolution spectra

The near-infrared emission lines of Fe$^{+}$ at 1.257, 1.321, and 1.644 $\mu$m share the same upper level; their ratios can then be exploited to derive the extinction to a line emitting region once the relevant spontaneous emission coefficients are known. This is commonly done, normally from low-resolution spectra, in observations of shocked gas from jets driven by Young Stellar Objects. In this paper we review this method, provide the relevant equations, and test it by analyzing high-resolution ($R \sim 50000$) near-infrared spectra oftwo young stars, namely the Herbig Be star HD 200775 and the Be star V1478 Cyg, which exhibit intense emission lines. The spectra were obtained with the new GIANO echelle spectrograph at the Telescopio Nazionale Galileo. Notably, the high-resolution spectra allowed checking the effects of overlapping telluric absorption lines. A set of various determinations of the Einstein coefficients are compared to show how much the available computations affect extinction derivation. The most recently obtained values are probably good enough to allow reddening determination within 1 visual mag of accuracy. Furthermore, we show that [FeII] line ratios from low-resolution pure emission-line spectra in general are likely to be in error due to the impossibility to properly account for telluric absorption lines. If low-resolution spectra are used for reddening determinations, we advice that the ratio 1.644/1.257, rather than 1.644/1.321, should be used, being less affected by the effects of telluric absorption lines.Comment: 17 pages, 6 figures, to be published in PAS

Proceedings of the Fifth Italian Conference on Computational Linguistics CLiC-it 2018

On behalf of the Program Committee, a very warm welcome to the Fifth Italian Conference on Computational Linguistics (CLiC-­‐it 2018). This edition of the conference is held in Torino. The conference is locally organised by the University of Torino and hosted into its prestigious main lecture hall “Cavallerizza Reale”. The CLiC-­‐it conference series is an initiative of the Italian Association for Computational Linguistics (AILC) which, after five years of activity, has clearly established itself as the premier national forum for research and development in the fields of Computational Linguistics and Natural Language Processing, where leading researchers and practitioners from academia and industry meet to share their research results, experiences, and challenges

Stereoselektive CC-Verknüpfungen: synthesen und anwendungen von dendritische Organokatalysatoren und polycyclische Kohlenwasserstoffgerüste

The present work consists of two different parts in which the synthesis and application of a dendritic hyperbranched polyglycerol supported organocatalysts and of enantioenriched polycyclic hydrocarbon scaffolds are described. In the first part, the efficiency of hyperbranched polyglycerol (PG) as a dendritic high loading platform for catalyst immobilization was evaluated in a study carried out in collaboration with Dr. M. K. Muthyala. Three different multivalent organocatalysts, characterized by a low (PG-30), an intermediate (PG-57) and a high degree (PG-95) of peripheral functionalization of the polymeric support, were synthesized using coppercatalyzed alkyne azide cycloadditions. Their application in the asymmetric Friedel–Crafts alkylation of N-methylpyrrole showed that multivalent PG-57 was the most active catalyst. The final recycling of PG-57 demonstrated that hyperbranched polyglycerol is an efficient and convenient support for organocatalysts immobilization. In the second part, the synthesis of large-ring propellanes and of a bridgehead bicyclo[4.4.4]tetradecadiene starting from closely related bicyclic frameworks are reported. The preparation of propellanes was carried out in collaboration with Dr. L. M. Schneider and Dr. V. M. Schmiedel. Conjugate additions of vinyl cuprates to Hajos–Parrish and Wieland–Miescher ketone derivatives, followed by ring-closing metathesis, gave access to the propellanes. This methodology was applied for obtaining highly enantioenriched (>99% ee) propelladienes as new chiral steering ligands for metal-catalyzed transformations. It was observed that the application of rigid polycyclic scaffolds in the asymmetric Rh-catalyzed arylation of cyclic enones led to a high turnover frequency of the active catalyst. The highly strained bridgehead bicyclo[4.4.4]tetradecadiene was prepared through skeletal rearrangement of a bicyclic Wieland–Miescher derivative. A tandem sigmatropic reaction was used to install the two bridgehead double bonds. Finally, strain-driven intramolecular C–C bond formations permitted the synthesis of bridged medium-sized carbocycles from the caged diene in a diversity-oriented fashion.Die vorliegende Arbeit ist aus zwei verschiedenen Teilen zusammengesetzt. Zum Einen wird die Synthese und Anwendung von an dendritisch Polyglycerol immobilisierten konjugierten Organokatalysatoren beschrieben und zum Anderen die Darstellung von enantiomerenangereicherten polycyclischen Kohlenwasserstoffgerüsten untersucht. Im ersten Projekt wurde in Zusammenarbeit mit Dr. M. K. Muthyala die Effizienz von hochverzweigtem Polyglycerin (PG) als dendritisch Trägermaterial für die Katalysatorimmobilisierung untersucht. Drei verschiedene multivalente Organokatalysatoren wurden via kupferkatalysierter Alkin-Azid-Cycloaddition synthetisiert. Sie unterschieden sich durch ein niedriges (PG-30), ein mittleres (PG-57) und ein hohes Maß (PG-95) der peripheren Funktionalisierung des polymeren Trägers. Bei deren Anwendung in der asymmetrischen Friedel–Crafts Alkylierung von N-Methylpyrrol zeigte sich, dass das multivalente PG-57 am aktivsten war. Zudem konnte gezeigt werden, dass die immobilisierten Organokatalysatoren leicht abgetrennt und recycelt werden können für zwei Zyklen. Die Ergebnisse demonstrieren, dass hochverzweigtes Polyglycerin eine effizientes Trägermaterial für die Immobilisierung von Organokatalysatoren darstellt. Im zweiten Teil sind die Synthesen von Großring-Propellanen und von einem Brückenkopf- Bicyclo[4.4.4]tetradecadien ausgehend von eng verwandten bicyclischen Gerüsten beschrieben. Die Herstellung der Propellane erfolgte in Zusammenarbeit mit Dr. L. M. Schneider und Dr. V. M. Schmiedel. Die konjugierte Addition von Vinylcupraten an Hajos–Parrish- und Wieland–Miescher-Ketonderivaten, gefolgt von einer Ringschlussmetathese ermöglichte die Darstellung von Propellanen. Diese Methode wurde ebenfalls angewendet, um hoch enantiomerenangereicherte (>99% ee) Propelladiene als neue chirale Dienliganden für metallkatalysierte Reaktionen zu erhalten. Es wurde beobachtet, dass die Anwendung von starren polycyclischen Gerüsten in der asymmetrischen Rh-katalysierten Arylierung von cyclischen Enonen zu einer hohen Umsatzfrequenz des aktiven Katalysatorsführte. Die hoch gespanntes Brückenkopf-Bicyclo[4.4.4]tetradecadien konnte durch die Gerüstumlagerung eines bicyclischen Wieland–Miescher-Decalins erreicht werden. Die spannungsgesteuerte intrinsische C–C-Brückenbindungsbildung generierte in einer Diversitäts-orientierten Weise verbrückten, mittelgroßen Carbocyclen aus dem Käfig-Dien

Multivalent polyglycerol supported imidazolidin-4-one organocatalysts for enantioselective Friedel–Crafts alkylations

The first immobilization of a MacMillan’s first generation organocatalyst onto dendritic support is described. A modified tyrosine-based imidazolidin-4-one was grafted to a soluble high-loading hyperbranched polyglycerol via a copper-catalyzed alkyne–azide cycloaddition (CuAAC) reaction and readily purified by dialysis. The efficiency of differently functionalized multivalent organocatalysts 4a–c was tested in the asymmetric Friedel–Crafts alkylation of N-methylpyrrole with α,β-unsaturated aldehydes. A variety of substituted enals was investigated to explore the activity of the catalytic system which was also compared with monovalent analogues. The catalyst 4b showed excellent turnover rates and no loss of activity due to immobilization, albeit moderate enantioselectivities were observed. Moreover, easy recovery by selective precipitation allowed the reuse of the catalyst for three cycles

Alkoxyallene-Based Stereodivergent Syntheses of (−)-Hyacinthacine B₄ and of Putative Hyacinthacine C₅ Epimers: Proposal of Hyacinthacine C₅ Structure

Hyacinthacines are members of the class of polyhydroxylated pyrrolizidines exhibiting outstanding biological activity as glycosidases inhibitors. Their structural complexity is embodied in the densely functionalized core, possessing a series of contiguous stereogenic centers. In this synthetic study we report a route to the more complex congeners of this class of alkaloids exploiting the diastereoselective addition of an axially chiral lithiated alkoxyallene to an enantiopure cyclic nitrone. Our stereodivergent approach enabled the installation of the targeted configuration at the ring A by minimal synthetic manipulations and at ring B by using stage dependent selective functionalizations. The versatility and robustness of this methodology were demonstrated by the syntheses of (−)-hyacinthacine B₄ and of two epimers of (+)-hyacinthacine C₅, allowing a suggestion of the likely structure of the isolated natural product

Asymmetric Synthesis of Carbocyclic Propellanes

A modular synthesis of functionalized carbocyclic propellanes was developed. Formation of the first of two quaternary bridgehead centers has been achieved by desymmetrization of prostereogenic ketones by either Hajos–Parrish–Eder–Sauer–Wiechert-type processes or Werner’s catalytic asymmetric Wittig reaction. The obtained bicyclic enones were subjected to conjugate additions upon which the remaining ring was formed by olefin metathesis. All bridges are amenable to further derivatization, which renders those compounds useful as central units in fragment-based drug discovery or as ligand scaffolds

Long-term albumin administration in decompensated cirrhosis (ANSWER): an open-label randomised trial

Background Evidence is scarce on the efficacy of long-term human albumin (HA) administration in patients with decompensated cirrhosis. The human Albumin for the treatmeNt of aScites in patients With hEpatic ciRrhosis (ANSWER) study was designed to clarify this issue.Methods We did an investigator-initiated multicentre randomised, parallel, open-label, pragmatic trial in 33 academic and non-academic Italian hospitals. We randomly assigned patients with cirrhosis and uncomplicated ascites who were treated with anti-aldosteronic drugs (>= 200 mg/day) and furosemide (>= 25 mg/day) to receive either standard medical treatment (SMT) or SMT plus HA (40 g twice weekly for 2 weeks, and then 40 g weekly) for up to 18 months. The primary endpoint was 18-month mortality, evaluated as difference of events and analysis of survival time in patients included in the modified intention-to-treat and per-protocol populations. This study is registered with EudraCT, number 2008-000625-19, and ClinicalTrials. gov, number NCT01288794.Findings From April 2, 2011, to May 27, 2015, 440 patients were randomly assigned and 431 were included in the modified intention-to-treat analysis. 38 of 218 patients died in the SMT plus HA group and 46 of 213 in the SMT group. Overall 18-month survival was significantly higher in the SMT plus HA than in the SMT group (Kaplan-Meier estimates 77% vs 66%; p=0.028), resulting in a 38% reduction in the mortality hazard ratio (0.62 [95% CI 0.40-0.95]). 46 (22%) patients in the SMT group and 49 (22%) in the SMT plus HA group had grade 3-4 non-liver related adverse events.Interpretation In this trial, long-term HA administration prolongs overall survival and might act as a disease modifying treatment in patients with decompensated cirrhosis. (C) 2018 Elsevier Ltd. All rights reserved