1,721,064 research outputs found
SYNTHESIS OF NEW TRYPTAMINE DERIVATIVES FOR BIOLOGICAL INVESTIGATION AS ANTITUMOR AGENTS
No full textRuthenium-Thymine Acetate binding modes
No full textNucleobases coordinated to Ruthenium centres have shown several promising properties for cancer treatments, demonstrating to have efficiency comparable to that of cis-Pt compounds, limiting toxic effects to intact cells and overcoming the drugs resistance after longer treatments. Thymine acetate (THAc) is proposed as a biomimetic model ligand to design potential Ruthenium-based antitumor drugs. Herein we report the reaction between Ru(H)2(CO)(PPh3)3, 1 and THAcH. The X-ray structure of the mono-,dihapto-thymine acetate species [(k1-O)(k2-O,O)Ru(THAc)2(CO)(PPh3)2] 2, unexpectedly exhibits cis-location for acetate ligands, likely ascribed to the prevalence of H-bonds and -stacking interactions. Conversely, DFT-calculations and NMR spectra suggest lower energy for the trans form where there are no contacts between the bulky phosphines. The DFT-calculated energies suggest the nature for NMR-intercepted plausible k1- or k2-intermediates. The carboxy-metal coordination is able to stabilize enol-tautomers through supramolecular H-interactions. The rotations of k1- and k2-acetate side arm of the THAc have also been exploited by correlating NMR signal patterns with the DFT energies.
Figure 1: Torsional barrier of k1-(O) 3 and k2-(O,O)
L’uso dei risultati del Questionario di Percezione delle Competenze Strategiche (QPCS) nell’ambito di un percorso di orientamento in ingresso con studenti universitari. L’esperienza del Piano Lauree Scientifiche (PLS) - Chimica dell’Università di Bologna
Full text linkUso del QPCS con matricole universitarie (PLS–Chimica Unibo) dall’a.a. 2018-19, con ipotesi di partenza::::: lo sviluppo dell’autodirezione nell’apprendimento favorisce la continuità negli studi. Il percorso è in tre fasi:: a) somministrazione del QPCS a matricole chimiche (N=436); b) restituzione in presenza dei risultati; c) tutorato a 44 studenti. Riflessioni:: modalità di restituzione,
uso dei risultati QPCS, reazioni degli studenti. Obiettivo:: costruire un quadro concettuale per futura ricerca.Use of QPCS with first-year university students (PLS - Chemistry University of Bologna) from 2018-19. Starting hypothesis: the development of selfdirection in learning promotes continuity in studies. Three-phases project: a) administration of QPCS to first-year students of chemistry (N = 436); b) in presence restitution of results; c) tutoring to 44 students. Reflections: restitution
methods, use of QPCS results, student reactions. Goal:: to construct a conceptual framework for future research
Reactions of Hydroxypyridines with 1-Chloro-2,4,6-trinitrobenzene − Product Structure, Kinetics, and Tautomerism
No full textReactions between 1-chloro-2,4,6-trinitrobenzene and 2-hydroxypyridine, 3-hydroxypyridine, and 4-hydroxypyridine are reported. 4-Hydroxypyridine produces the product of attack at the nitrogen atom, while 3-hydroxypyridine reacts at the oxygen atom. 2-Hydroxypyridine reacts as an ambidentate nucleophile, providing a mixture of products arising from attack at both the oxygen and the nitrogen atom. Reactions between X-substituted-3-hydroxypyridines (X = H, 5-Cl, 6-CH3) and 1-chloro-2,4,6-trinitrobenzene provided 3-pyridinyl 2,4,6-trinitrophenyl ethers, analysed by H-1 and C-13 NMR spectra and by X-ray diffraction. Moderate heating of methanolic solutions of 3-pyridinyl 2,4,6-trinitrophenyl ether and of 6-methyl-3-pyridinyl 2,4,6-trinitrophenyl ether caused a methylation reaction of the pyridine nitrogen ring through trinitroanisole, providing 3-hydroxy-1-methylpyridinium picrate and 1,2-dimethyl-5-hydroxypyridinium picrate. Kinetic data are compared and discussed
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
“Synthesis and Antiproliferative study of Ru(II) – Hydroxy Stearic Acids ”
No full textProspectives on Ruthenium anticancer agents are encouraging since Ru(II) can directly interact on tumor cells via multiple mechanisms provoking their death. The selection of ligands plays a key role in anticancer activity, the addition of hydrophobic species such as PPh3 to a metal center increases drug uptake in cancer cells and could allow the intercalation in DNA nucleobases pairs. Metallodrugs often show an enhanced anticancer activity compared to free ligands.
In this context, ligands with well-established antitumor activity as 7- and (R)-9-Hydroxy stearic acid (HSA) were selected and reacted with mer-[Ru(H)2(CO)(PPh3)3] to give Ru(II) anticancer species.2 The anticancer in vitro properties of this class of metallo-prodrugs could be ascribed to synergistic effects between the metal center and bioactive ligands. The results have been compared with the analogously coordinated innocuous 12-HSA. The three novel Ru(II)-HSA complexes were fully characterized spectroscopically by using ESI-MS, IR, UV-Vis, and NMR techniques. The nature of Ru-12-HSA was also determined by single crystal X-ray diffraction, Cytotoxicity, cell proliferation, and DNA damage tests were performed demonstrating the biological activity of Ru-7-HSA and Ru-9-HSA
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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