1,158 research outputs found
Organocatalytic vinylogous Mannich reaction of trimethylsiloxyfuran with isatin-derived benzhydryl-ketimines
No full textA family of chiral quaternary 3-aminooxindole butenolides has been synthesized by BINOL-derived phosphoric acid-catalyzed addition of trimethylsiloxyfuran to isatin-derived ketimines. Such a vinylogous Mannich-type reaction was found to produce diastereoisomeric butenolides in good yields and in most cases high enantiomeric excesses. The configurational assignment of the obtained products was safely performed by chemical correlation. A computational study of the transition state allowed rationalizing the obtained stereochemical outcome, highlighting the possible binding modes of the catalyst-imine-nucleophile transition complex
Giulia Veronica Varisco
No full textThe headword explains the biography and the contribution of the author Giulia Varisco to the children's literatur
Biocatalysed olefin reduction of 3-alkylidene oxindoles by baker's yeast
Get PDF3-Substituted oxindoles are very interesting molecules both for their potential biological activity and for their role as starting materials toward more complex oxindole-based structures. These molecules can be prepared by the reduction of a 3-ylidene oxindole precursor by classical metal-catalysed chemical reductions of the olefin. In this work we present a biocatalytic approach for the reduction of oxindole-based olefins using baker's yeast. All the substrates were efficiently reduced in high yields. When an α,Î2-unsaturated ketone was used, the corresponding saturated alcohol was obtained in high yield and ee. To further investigate the enzyme-substrate interactions a molecular docking study was also performed
Multicomponent Approach to Bioactive Peptide-Ecdysteroid Conjugates: Creating Diversity at C6 by Means of the Ugi Reaction
No full textAn efficient multicomponent protocol has been developed to access two different kinds of peptide–ecdysteroid conjugates. The approach exploits the reactivity of the 6-keto-7-ene group of 20-OH-ecdysone, allowing the unprecedented preparation of 6-amino and 6-isocyanide derivatives. The ecdysteroid derivatives were further employed in the Ugi reaction, together with formaldehyde and various structurally diverse carboxylic acids, isocyanides and amines, to afford a small family of potential multidrug-resistance modulators
Organocatalytic Asymmetric Biginelli-like Reaction Involving Isatin
Get PDFThe first asymmetric, Brønsted acid catalyzed Biginelli-like reaction of a ketone has been developed, employing N-substituted isatins as carbonyl substrates, and urea and alkyl acetoacetates as further components. BINOL-derived phosphoric acid catalysts have been used to achieve the synthesis of a small library of chiral, enantioenriched spiro(indoline-pyrimidine)-diones derivatives. The absolute configuration of the new spiro stereocenter was assessed on diastereoisomeric derivatives through computer-assisted NMR spectroscopy. X-ray diffractometry allowed the disclosure of the overall molecular conformation in the solid state and the characterization of the crystal packing of a Br-substituted Biginelli-like derivative, while computational studies on the reaction transition state allowed us to rationalize the stereochemical outcome
The Carnal Specter: The Virtual Reality User Against Fragmentation
Get PDFSince Virtual Reality (VR) is characterised by the absence of the frame, the VR user has the impression of being immersed into the image, thus overcoming the distinction between spectacle and spectator. Therefore, the user becomes herself part of the work of art, exposing the limits of the Cartesian dualisms dominating the Western thought and raising critical questions about traditional aesthetic categories. Hence, my paper aims at pondering on the ontological status of the VR user. In opposition to Simon Penny’s argument, which proposes that VR fragments the viewer into a physical body versus a virtual one, my research goal is to clarify that the participant’s physical body and virtual body are inseparable and firmly intertwined. In order to do so, I analyse the VR documentary Send me Home (Evanisko, 2019). The point of departure is the acknowledgment that the VR user is invisible both to herself and to the other characters with whom she shares the virtual space. Following Jacques Derrida’s Specters of Marx, I argue that this invisibility reveals the ontological status of the VR participant as a specter. However, my goal is to show that the spectrality of the user is not in contradiction with her carnality: on the contrary, even when one tries to bracket the body, the body remains vigilant, interpreting the world through its flesh. To conclude, then, I argue that the body is the condition of possibility for the user to feel immersed into the virtual world, and that, contrary to the fragmentation argument, physical body and virtual body cannot be thought as separate.Since Virtual Reality (VR) is characterised by the absence of the frame, the VR user has the impression of being immersed into the image, thus overcoming the distinction between spectacle and spectator. Therefore, the user becomes herself part of the work of art, exposing the limits of the Cartesian dualisms dominating the Western thought and raising critical questions about traditional aesthetic categories. Hence, my paper aims at pondering on the ontological status of the VR user. In opposition to Simon Penny’s argument, which proposes that VR fragments the viewer into a physical body versus a virtual one, my research goal is to clarify that the participant’s physical body and virtual body are inseparable and firmly intertwined. In order to do so, I analyse the VR documentary Send me Home (Evanisko, 2019). The point of departure is the acknowledgment that the VR user is invisible both to herself and to the other characters with whom she shares the virtual space. Following Jacques Derrida’s Specters of Marx, I argue that this invisibility reveals the ontological status of the VR participant as a specter. However, my goal is to show that the spectrality of the user is not in contradiction with her carnality: on the contrary, even when one tries to bracket the body, the body remains vigilant, interpreting the world through its flesh. To conclude, then, I argue that the body is the condition of possibility for the user to feel immersed into the virtual world, and that, contrary to the fragmentation argument, physical body and virtual body cannot be thought as separate
Ytterbium Disilicate/Monosilicate Multilayer Environmental Barrier Coatings: Influence of Atmospheric Plasma Spray Parameters on Composition and Microstructure
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Ytterbium Disilicate/Monosilicate Multilayer Environmental Barrier Coatings: Influence of Atmospheric Plasma Spray Parameters on Composition and Microstructure
by Giulia Di Iorio,Laura Paglia *ORCID,Giulia PedrizzettiORCID,Virgilio GenovaORCID,Francesco MarraORCID,Cecilia BartuliORCID andGiovanni PulciORCID
INSTM Reference Laboratory for Materials and Surface Engineering, Sapienza University of Rome, Eudossiana 18, 00184 Rome, Italy
*
Author to whom correspondence should be addressed.
Coatings 2023, 13(9), 1602; https://doi.org/10.3390/coatings13091602
Original submission received: 10 August 2023 / Revised: 31 August 2023 / Accepted: 11 September 2023 / Published: 13 September 2023
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Abstract
SiC/SiC ceramic matrix composites (SiCf/SiC CMCs) are regarded as the new materials for the hot-section components of aircraft gas turbine engines, since they have one-third of the density of metallic superalloys, a higher temperature capability, good mechanical strength, and excellent thermal shock resistance. However, high-temperature water-vapor-rich combustion gases can induce severe surface recession phenomena in SiC/SiC leading to component failure. For this reason, it is necessary to design protective coatings, i.e., environmental barrier coatings (EBCs), able to protect the SiC/SiC surface in combustion environments. In the present work, ytterbium monosilicate (Yb2SiO5), stable when exposed to water vapor at high temperatures, and ytterbium disilicate (Yb2Si2O7), characterized by a thermal expansion coefficient closer to that of the substrate, were selected for a multilayer EBC system. EBCs were processed using the atmospheric plasma spray (APS) technique. A set of deposition parameters were tested, varying the power of the torch, and the composition and microstructure of the deposited coatings were studied in terms of porosity, crack density, and post-deposition phase retention by performing SEM, EDS, and XRD analysis. The results allow for the definition of the influence of deposition parameters on the final properties of multilayer EBC coatings
Correction to: Safety and Psychological Outcomes of Tandem t:Slim X2 Insulin Pump with Control-IQ Technology in Children, Adolescents, and Young Adults with Type 1 Diabetes: A Systematic Review
Get PDFThe second author name was incorrectly published as Giula Maria Smylie. The correct name is Giulia Marie Smylie. The original article has been corrected
Organocatalytic Access to Enantioenriched Spirooxindole-Based 4-Methyleneazetidines
Get PDFThis work describes the synthesis of enantioenriched spiro compounds, incorporating the azetidine and the oxindole motifs. The preparation relies on a formal [2 + 2] annulation reaction of isatin-derived N-tert-butylsulfonyl ketimines with allenoates. The asymmetric induction is secured by an organocatalytic strategy, exploiting a bifunctional cinchona-type β-isocupridine-based catalyst. Some post-transformation products, including unexpected spiropyrroline and 3,3-disubstituted oxindole derivatives, are also presented
Scrivere senza anestesia. La chiarezza di Giulia Niccolai
No full textIl saggio colloca storicamente la narratrice e poetessa Giulia Niccolai nel canone del Novecento letterario italiano discutendone poetica e cifre stilistiche. L'ampia analisi proposta tocca tutte le opere dell'autrice evidenziandone i legami intertestuali, anche tra poesia e narrativa, e i progressivi sviluppi in un arco cronologico esteso, tra anni Sessanta e primi anni Duemila. Lo studio coglie anche l'importanza dei riferimenti alle arti visive, in particolare alla fotografia, che Giulia Niccolai ha praticato in prima persona negli anni della Neoavanguardia, e alla pittura americana.The essay places the narrator and poet Giulia Niccolai in the canonical twentieth century Italian literary discussing her poetics and stylistic figures. The wide analysis proposed touches all the works of the author highlighting the intertextual links, also between poetry and narrative, and the progressive developments in an extended chronological period, between the Sixties and early Twenties. The study also captures the importance of references to the visual arts, especially photography, which Giulia Niccolai has practiced in the years of the Neo-avant-garde, and to American painting
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