Sintesi e caratterizzazione di nuovi cluster carbonilici Rh-Sb e Rh-Ge

The topic of my thesis was focused on the synthesis of heteroatomic Rh clusters stabilized by carbonyl ligands. I studied the reactivity of [Rh7(CO)16]3- with different Sb3+ and Ge4+ salts, and tried to synthesize new species by changing the reaction conditions. Indeed, in order to obtain new Rh-Sb and Rh-Ge clusters, I employed different stoichiometric ratios, solvents and atmospheres (N2 or CO). As far as the Rh-Sb system is concerned, I successfully synthesized three new compounds through two different reactions, namely [Rh20Sb3(CO)36][NEt4]3, [Rh21Sb2(CO)38][NEt4]5 and [Rh12Sb(CO)24][NEt4]3. At the same time, I investigated the Rh-Ge system and succeeded in the isolation of the new cluster [Rh14Ge2(CO)30][NEt4]2, along with [Rh12SbGePh2(CO)26][NEt4]2, by treating [Rh7(CO)16]3- with both Ge4+ and Sb3+ salts. Each compound has been characterized by IR spectroscopy, ESI-MS spectrometry and single crystal X-ray diffractometry. Finally, I conduced chemical reactivity tests on some of the obtained compounds.

The velocity dispersion profile of the globular cluster 47Tucanae

Gli ammassi globulari rappresentano i laboratori ideali nei quali studiare la dinamica di sistemi ad N-corpi ed i suoi effetti sull’evoluzione stellare. Infatti, gli ammassi globulari sono gli unici sistemi astrofisici che, entro il tempo scala dell’età dell’Universo, sperimentano quasi tutti i processi di dinamica stellare noti. Questo lavoro di tesi si inserisce in un progetto a lungo termine volto a fornire una dettagliata caratterizzazione delle proprietà dinamiche degli ammassi globulari galattici. In questa ricerca, strumenti di fondamentale importanza sono il profilo di dispersione di velocità del sistema e la sua curva di rotazione. Per determinare le componenti radiali di questi profili cinematici in ammassi globulari galattici è necessario misurare la velocità lungo la linea di vista di un ampio campione di stelle membre, a differenti distanze dal centro. Seguendo un approccio multi-strumentale, è possibile campionare l’intera estensione radiale dell’ammasso utilizzando spettrografi multi-oggetto ad alta risoluzione spettrale nelle regioni intermedie/esterne, e spettrografi IFU con ottiche adattive per le regioni centrali (pochi secondi d’arco dal centro). Questo lavoro di tesi è volto a determinare il profilo di dispersione di velocità dell’ammasso globulare 47 Tucanae, campionando un’estensione radiale compresa tra circa 20'' e 13' dal centro. Per questo scopo sono state misurate le velocità radiali di circa un migliaio di stelle nella direzione di 47 Tucanae, utilizzando spettri ad alta risoluzione ottenuti con lo spettrografo multi-oggetto FLAMES montato al Very Large Telescope dell’ESO. Le velocità radiali sono state misurate utilizzando la tecnica di cross-correlazione tra gli spettri osservati e appropriati spettri teorici, e sono state ottenute accuratezze inferiori a 0.5km/s. Il campione così ottenuto (complementare a quello raccolto con strumenti IFU nelle regioni centrali) è fondamentale per costruire il profilo di dispersione di velocità dell’ammasso e la sua eventuale curva di rotazione. Questi dati, combinati col profilo di densità dell’ammasso precedentemente determinato, permetteranno di vincolare opportunamente modelli teorici come quelli di King (1966) o di Wilson (1975), e di arrivare così alla prima solida determinazione dei parametri strutturali e dinamici (raggi di core e di metà massa, tempo di rilassamento, parametro collisionale, etc.) e della massa totale e distribuzione di massa del sistema.

Analisi di un'architettura Multi-Master ad alta affidabilità basata su MariaDB Galera Cluster

Progettazione, realizzazione ed analisi prestazionale e di robustezza di un sistema di cluster ad alta affidabilità basato su MariaDB Galera Cluster. Affiancamento al cluster di un sistema di proxy MaxScale. Studio e realizzazione di una procedura di migrazione da DBMS MySQL a MariaDB Galera Cluster.

The tumour-suppressive miR-29a/b1 cluster is regulated by CEBPA and blocked in human AML

CCAAT/enhancer-binding protein-alpha (CEBPA) is crucial for normal granulopoiesis and is frequently disrupted in acute myeloid leukaemia (AML). Increasing evidence suggests that CEBPA exerts its effects, in parts, by regulating specific microRNAs (miRNAs), as previously shown for miR-223. The aim of this study was to investigate the genome-wide pattern of miRNAs regulated by CEBPA in myeloid cells.

A randomised determination of the effect of fluvastatin and atorvastatin on top of dual antiplatelet treatment on platelet aggregation after implantation of coronary drug-eluting stents. The EFA-Trial

Drug-drug interaction between statins metabolised by cytochrome P450 3A4 and clopidogrel have been claimed to attenuate the inhibitory effect of clopidogrel. However, published data regarding this drug-drug interaction are controversial. We aimed to determine the effect of fluvastatin and atorvastatin on the inhibitory effect of dual antiplatelet therapy with acetylsalicylic acid (ASA) and clopidogrel. One hundred one patients with symptomatic stable coronary artery disease undergoing percutaneous coronary intervention and drug-eluting stent implantation were enrolled in this prospective randomised study. After an interval of two weeks under dual antiplatelet therapy with ASA and clopidogrel, without any lipid-lowering drug, 87 patients were randomised to receive a treatment with either fluvastatin 80 mg daily or atorvastatin 40 mg daily in addition to the dual antiplatelet therapy for one month. Platelet aggregation was assessed using light transmission aggregometry and whole blood impedance platelet aggregometry prior to randomisation and after one month of receiving assigned statin and dual antiplatelet treatment. Platelet function assessment after one month of statin and dual antiplatelet therapy did not show a significant change in platelet aggregation from 1st to 2nd assessment for either statin group. There was also no difference between atorvastatin and fluvastatin treatment arms. In conclusion, neither atorvastatin 40 mg daily nor fluvastatin 80 mg daily administered in combination with standard dual antiplatelet therapy following coronary drug-eluting stent implantation significantly interfere with the antiaggregatory effect of ASA and clopidogrel.

Accurate Predictions of Water Cluster Formation, (H2O)n=2-10

An efficient mixed molecular dynamics/quantum mechanics model has been applied to the water cluster system. The use of the MP2 method and correlation consistent basis sets, with appropriate correction for BSSE, allows for the accurate calculation of electronic and free energies for the formation of clusters of 2−10 water molecules. This approach reveals new low energy conformers for (H2O)n=7,9,10. The water heptamer conformers comprise five different structural motifs ranging from a three-dimensional prism to a quasi-planar book structure. A prism-like structure is favored energetically at low temperatures, but a chair-like structure is the global Gibbs free energy minimum past 200 K. The water nonamers exhibit less complexity with all the low energy structures shaped like a prism. The decamer has 30 conformers that are within 2 kcal/mol of the Gibbs free energy minimum structure at 298 K. These structures are categorized into four conformer classes, and a pentagonal prism is the most stable structure from 0 to 320 K. Results can be used as benchmark values for empirical water models and density functionals, and the method can be applied to larger water clusters.

Inhibition of the miR-143/145 cluster attenuated neutrophil differentiation of APL cells

MicroRNAs can influence hematopoietic cell lineage commitment and aberrant expression of hematopoietic miRNAs contributes to AML pathology. We found that miR-143 and miR-145 expression is significantly repressed in primary AML patient samples as compared to neutrophils of healthy donors. Further analysis revealed impaired neutrophil differentiation of APL cells upon inhibition of miR-145 expression. Lastly, we identified p73 as transcriptional regulator of miR-143/145 during neutrophil differentiation of APL cells. Our data suggest that low miR-145 levels in APL, possibly due to aberrant expression of p73 transcription factors, contribute to the differentiation block seen in this disease.

Accurate Predictions of Water Cluster Formation, (H2O)n=2−10

An efficient mixed molecular dynamics/quantum mechanics model has been applied to the water cluster system. The use of the MP2 method and correlation consistent basis sets, with appropriate correction for BSSE, allows for the accurate calculation of electronic and free energies for the formation of clusters of 2−10 water molecules. This approach reveals new low energy conformers for (H2O)n=7,9,10. The water heptamer conformers comprise five different structural motifs ranging from a three-dimensional prism to a quasi-planar book structure. A prism-like structure is favored energetically at low temperatures, but a chair-like structure is the global Gibbs free energy minimum past 200 K. The water nonamers exhibit less complexity with all the low energy structures shaped like a prism. The decamer has 30 conformers that are within 2 kcal/mol of the Gibbs free energy minimum structure at 298 K. These structures are categorized into four conformer classes, and a pentagonal prism is the most stable structure from 0 to 320 K. Results can be used as benchmark values for empirical water models and density functionals, and the method can be applied to larger water clusters.

Diffusion tensor imaging in episodic cluster headache

Cluster headache (CH) is a rare headache disorder with severe unilateral headache bouts and autonomic symptoms. The pathophysiology of CH is not completely understood. Using a voxel-based morphometric paradigm or functional imaging, a key role of the hypothalamus and the pain matrix could be demonstrated during CH episodes. However, there are no diffusion tensor imaging (DTI) data investigating the white matter microstructure of the brain in patients with CH. Therefore, we used DTI to delineate microstructural changes in patients with CH in a headache-free state.