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MOLECULAR GOLD NANOCLUSTERS CAPPED BY N-HETEROCYCLIC CARBENE LIGANDS
Full text linkGold nanoparticles (AuNPs) and gold complexes are among the most studied chemical entities for their luminescence behavior and catalytic applications. However, other gold species started to attract worldwide scientific interest in the course of the last years: molecular gold nanoclusters (AuNCs). These are generally composed by several gold atoms forming a metallic core, in which part of the gold atoms are formally zerovalent. Despite their particle-like structure, AuNCs show molecular proprieties, such as a discrete orbital structure and a precise stoichiometric formula. So far, AuNCs stabilization has been mainly reached exploiting thiolate, alkynyl and phosphine ligands, which form a layer saturating and protecting the cluster core. However, the steric and electronic properties of such ligands cannot be independently varied. For this reason, N-heterocyclic carbenes (NHCs) are currently studied as alternative ligands to achieve core protection, also
considering the better stabilization obtained with these. Hitherto, AuNCs synthesis has been performed through gold complex reduction using NaBH4, although the reduction mechanism is still unknown and consequently this synthesis is complicate to control. Exploited this methodology, in this PhD thesis the ole of different NHCs has been investigated, showing as such ligands generally provide superatomic (SA) clusters, characterized by [Au11]3+ or [Au13]5+ metallic cores, presenting therefore a complete SA electronic configuration providing further stabilization of the cluster. The role of reducing agent and solvent has been also evaluated, underlining as it is possible to tune the reduction pathways, changing
therefore the reduction products. For instance, it is possible to obtain CH3 anionic ligands bind on clusters core when the reduction promoted by NaBH4 is performed in presence of CH2Cl2, used as solvent. Using instead hydrazine as reducing agent [Au6(C)]2+ clusters can be obtained. Notwithstanding the interesting products derived from these syntheses, these reductions are generally not selective, limiting therefore their use.
Considering these limitations, in this thesis we have developed another method to isolate such molecular species, called stepwise approach, in which the obtained AuNCs are stabilized by triphenylphosphine (PPh3) and di-NHCs. With this latter
method a reaction between a pre-formed PPh3-stabilized [Au11(PPh3)8Cl2]+ cluster and [(di-NHC)Au2Cl2] gold(I) complexes occurs. Depending on starting complex and reaction conditions, a metathesis cluster [Au11(di-NHC)(PPh3)6Cl2]+ is produced first, followed by formation of [Au13(di-NHC)2(PPh3)4Cl4]+ via a subsequent metal complex
addition. In some cases, a further metathesis takes place, providing [Au13(di-NHC)3(PPh3)3Cl3]2+. We have tested these clusters as anticancer pro-drugs, demonstrating as these can accumulate in cancer cells thanks to enhanced permeation and retention (EPR) effect, affording high anticancer efficiency too. Likely the antitumor activity derived from AuNCs degradation in biological environment, providing gold complexes acting like anticancer drugs. Finally, thanks to a collaboration with Prof. Dominik Munz at Saarland University(Germany), we have extended our studies towards the synthesis of an unsaturated and cubic palladium cluster and started also a study regarding the stabilization of gold
nanowires using NHC ligands
The Causes of Jesus’ Death in the Light of the Holy Bible and the Turin Shroud
No full textDue to the lack of information, the pathogenesis of the death of Jesus of Nazareth is still widely
debated. A univocal pathogenesis can be detected by the close comparison between what is reported in
the Holy Bible (in particular the four Gospels and the prophetic passages of the Old Testament) and what
can be observed on the Turin Shroud (TS). Obviously the authenticity of the latter must be here accepted
in the sense that it wrapped the corpse of Jesus of Nazareth.
The criteria used to support or ignore many etiological hypotheses regarding the terminal event that caused Jesus’ death must take into account: an acute fact, the perfect lucidity and the cry of Jesus immediately before his death. We conclude that the causes of death are: Terminal cause: myocardial infarction, heart rupture and hemopericardium. Contributing and accelerating causes, in chronological order: 1. severe emotional stress and sweating with hematohydrosis, 2. fluid loss without drinking, 3. beating and scourging, 4. crown of thorns, 5. blunt trauma to the neck and thorax following the fall with right shoulder dislocation, paralysis of the entire right brachial plexus, pulmonary contusion with hemothorax and cardiac contusion, 6. nailing, 7. probable left ulnar proximal paralysis from stretching during crucifixion, 8. probable right foot dislocation from stretching during crucifixion, 9. causalgia, 10. Hypoventilation, 11. Hemorrhagic-hypovolemic-politraumatic and suspension shock
SIGNAL - Device interattivo ad alta tecnologia per la sicurezza nella mobilità dolce
No full textIl prodotto in oggetto prende il nome di SIGNAL: si tratta di un dispositivo tecnologico per i mezzi della mobilità dolce, ovvero biciclette e monopattini elettrici. L’obiettivo del suo funzionamento è rendere più sicuri gli spostamenti effettuati con mezzi leggeri, che spesso si trovano a stretto contatto con grandi veicoli motorizzati, così da evitare incidenti. Il corpo centrale prende la forma di una pillola allungata, la forma è quindi affusolata e non presenta importanti spigoli vivi. I due supporti da manubrio sono simili invece alla lettera greca ρ (rho), la basetta di ricarica è invece di forma cilindrica e poco allungata
From Au(11) to Au(13): Tailored Synthesis of Superatomic Di-NHC/PPh(3)-Stabilized Molecular Gold Nanoclusters
Full text link[Image: see text] Herein, we report a new method to synthesize molecular gold nanoclusters (AuNCs) stabilized by phosphine (PR(3)) and di-N-heterocyclic carbene (di-NHC) ligands. The interaction of di-NHC gold(I) complexes, with the general formula [(di-NHC)Au(2)Cl(2)] with well-known [Au(11)(PPh(3))(8)Cl(2)]Cl clusters provides three new classes of AuNCs through a controllable reaction sequence. The synthesis involves an initial ligand metathesis reaction to produce [Au(11)(di-NHC)(PPh(3))(6)Cl(2)](+) (type 1 clusters), followed by a thermally induced rearrangement/metal complex addition with the formation of Au(13) clusters [Au(13)(di-NHC)(2)(PPh(3))(4)Cl(4)](+) (type 2 clusters). Finally, an additional metathesis process yields [Au(13)(di-NHC)(3)(PPh(3))(3)Cl(3)](2+) (type 3 clusters). The electronic and steric properties of the employed di-NHC ligand affect the product distribution, leading to the isolation and full characterization of different clusters as the main product. A type 3 cluster has been also structurally characterized and was preliminarily found to be strongly emissive in solution
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
Commentary on: Borrini M, Garlaschelli L. A BPA approach to the Shroud of Turin. J Forensic Sci https://doi.org/10.1111/1556-4029.13867. Epub 2018 July 10
No full textVariations 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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