187,779 research outputs found
Alkyne Hydroamination Promoted by NHC-Gold(I) Complexes: Activity and Mechanistic Insight
No full textThe pharmaceutical and chemical industries heavily rely on the production of N-containing
compounds, as these molecules serve as scaffolds for the synthesis of both fine chemicals and
polymers of interest. The hydroamination reaction can be hailed as a paradigm of a
contemporary, sustainable, catalytically promoted chemical process, since it can form C-N
bonds by adding amines to multiple carbon bonds with a 100% atom economy.1 By reducing
the high energy barriers connected to alkyne activation, use of metal complexes can facilitate
this process; lately, gold(I) N-heterocyclic (NHC) complexes were demonstrated to be
promising in this regard.2 Herein, we present a library of gold(I)-NHC complexes which were
identified as promising catalysts for regioselective Markovnikov addition of aromatic and
aliphatic alkynes to anilines, with high yields.3 Accurate catalyst’ design, experimental reaction
scope and computational mechanistic insight will be presented, by means of which the nonmonotonic
impact of substrate substituents on the reaction course was elucidated.
References
(1) Müller, T. E.; Hultzsch, K. C.; Yus, M.; Foubelo, F.; Tada, M. Chem. Rev. 2008, 108, 3795–3892.
(2) Mariconda, A.; Sirignano, M.; Troiano, R.; Russo, S.; Longo, P. Catalysts 2022, 12(8), 836.
(3) Sirignano, M.; D’Amato, A.; Costabile, C.; Mariconda, A.; Crispini, A.; Scarpelli, F.; Longo, P. Front. Chem.
2023, 11, 1260726
I traumi dell’uretere: contributo casistico e spunti medico- legali
No full textI traumi dell’uretere: contributo casistico e spunti medico- legal
Commentary. Subintimal angioplasty of femoropopliteal artery occlusions: the long-term results
No full textClaimants in vascular surgery
No full textLitigation concerning medical activities is constantly increasing, as society becomes more and more “protective” of citizens who may have suffered any wrong due to malpractice. However, we should bear in mind that the percentage of claims liquidated is minimal.
Methods. From January 2009 to December 2011, 63 claims involving vascular procedures were analyzed. The rate of claimants receiving payment was very low: only 8 of the 63 (12.7%) claims having been settled. The most important thing we noted was that in 5 of the 8 claims settled the key element that defined the sentence was time: time to take a decision, to perform a diagnostic examination, to decide on a surgical procedure.
Results. We have sought to assess the role of the “time factor” in the occurrence of errors in a surgical specialty considered at high risk of litigation such as vascular surgery. This analysis of our experience over the past three years has shown that the central element in the genesis of the error was the erroneous timing of intervention. It interesting to note that, in contrast to what might be expected, time-related errors are much more common in cases treated electively than in urgent or emergency cases.
Conclusion. Our experience demonstrates that the “time factor” plays a primary role in the genesis of errors in vascular surgery. This delay in deciding and acting probably depends on the fact that the vascular surgeon was the patient’s first contact in only one of the cases examined. This should emphasize the need to equip all emergency departments with a Vascular Surgery Unit
Commentary: The ENABLER-P Balloon Catheter System: a new and exciting tool for recanalization of femoropopliteal CTOs
No full textStereoselective Copolymerization of Styrene with para-Substituted Styrenes Catalyzed by Half-Titanocenes: An Experimental and Computational Study
No full textCopolymerization of styrene (S) with p-methylstyrene (PMS) and
p-chlorostyrene (PCS), catalyzed by half-titanocenes (CpCH2CH2O)TiCl2 (1)
and (CpCH2CH2OCH3)TiCl3 (2) activated by methylaluminoxane (MAO), was
investigated from both experimental and computational points of view. The
reactivity ratios and syndioselectivity of the reaction are affected by the styrene
derivative and the catalytic system, leading to the formation of block or random
copolymers. Using both catalytic systems, styrene, p-methylstyrene, and pchlorostyrene
show the same reactivity trend (PMS > S > PCS) already reported
in the presence of the CpTiCl3/MAO catalyst and in the syndiotactic and isotactic
polymerization of styrene derivatives with other Ti-based catalysts. According to density functional theory (DFT) calculations,
extended also to the CpTiCl3/MAO catalyst, the reactivity of the employed comonomers is mainly due to the different electrondonating
character of monomer para-substituents. As for stereoselectivity, (1) and (2) lead to syndiotactic copolymer sequences
with PMS and S, whereas a loss of selectivity is observed in the poly-p-chlorostyrene homosequences of PCS/S copolymers.
According to DFT studies, this lack of selectivity can be attributed to the presence of a σ terminal growing chain in the insertion
transition states when PCS is involved in the polymerization
EDUCATION AND NARRATION IN INTERCULTURAL PERSPECTIVE: THEORIES AND INTERVENTIONS
No full textThe article analyzes the issue of educational practices focusing on narration
and autobiography. The theoretical and methodological framework used is that of
intercultural education and action research in education. In this perspective, the authors
present some approaches to narrative and autobiographical educational interventions
and, finally, are presented the data related to a research on immigrant children in Italy
La mortalità perinatale nell’Ospedale di Tolentino dal 1972 al 1987
No full textIl numero delle morte perinatali è stato oggetto di studio presso l'ospedale di Tolentino negli anni 1972 al 198
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