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SIGNIFICATO PROGNOSTICO DELLE CELLULE TUMORALI CIRCOLANTI (CTC) NELLE NEOPLASIE SOLIDE DI COLON E MAMMELLA
No full textINVOLVEMENT OF BH4 DOMAIN OF BCL-2 IN THE REGULATION OF HIF-1-MEDIATED VEGF EXPRESSION IN HYPOXIC TUMOR CELLS
No full textAnalisi del sistema elettrico italiano e possibili azioni di indirizzo. Scenari di evoluzione del sistema elettrico italiano nel medio lungo termine: impatto di nuove tecnologie sulla domanda elettrica e prospettive di sviluppo del sistema di offerta - Analisi con un modello Markal-Times del sistema elettrico italiano
No full textStructural transition and phase separation studies for superconducting material designing
No full textThe recent discovery of high-temperature superconductivity (HTS) in the iron pnictides [1] has provided a new class of materials for the search of the physical mechanism that allows a quantum coherent condensate to avoid the effects of temperature decoherence. The discovery of HTS in was soon followed by the discovery of a different class of superconducting iron-based compounds, among which the quaternary systems “1111” (REFeAsO, RE stands for rare earth) and ternary "122" , A stands for Ba, Ca, Sr, etc.) systems are the most investigated. Superconductivity arises in the 1111 systems by the partial fluorine substitution for the oxygen, or by the creation oxygen defects. On the other hand, substitution of Fe by K, Ni, etc. is found to result in the superconducting transition in the 122 systems. Interestingly, in both cases, the bulk superconductivity appears by the suppression of the long-range magnetic ordering of the parent compounds. The parent compounds, which do not show superconductivity (SC), show a structural transition from the room temperature tetragonal to the low temperature orthorhombic structure. In the 1111 systems, the structural and magnetic transitions do not coincide, whereas the structural and magnetic transitions coincide in the 122 systems.
The tetragonal-to-orthorhombic structural phase transition (SPT) in LaFeAsO (La-1111) and SmFeAsO (Sm-1111) single crystals measured by high-resolution x-ray diffraction is found to be sharp while the RFeAsO (R=La, Nd, Pr, Sm) polycrystalline samples show a broad continuous SPT. Comparing the polycrystalline and the single-crystal 1111 samples, the critical exponents of the SPT are found to be the same while the correlation length critical exponents are found to be very different. These results imply that the lattice fluctuations in 1111 systems change in samples with different surface to volume ratio that is assigned to the relieve of the temperature-dependent superlattice misfit strain between active iron layers and the spacer layers in 1111 systems. This phenomenon that is missing in the (A=Ca, Sr, Ba) “122” systems, with the same
electronic structure but different for the thickness and the elastic constant of the spacer layers, is related with the different maximum superconducting transition temperature in the 1111 (55 K) versus 122 (35 K) systems and implies the surface reconstruction in 1111 single crystals.
Superconductivity has been induced by oxygen defects in the fluorite spacers in iron-based oxypnictides , and with the maximum critical temperature being 43, 51.9 and 52 K, respectively. Oxygen defects induce electron doping of the Fe derived bands crossing the Fermi level and the electronic/magnetic structure is very sensitive to different atomic substitutions and rare-earth (RE) ions.
The change of the RE atomic radius induces a change of the elastic misfit strain between the superconducting Fe layers and the intercalated layers, like in cuprates, and diborides.
Superconductivity, with transition temperature, , above 30 K, has been reported also in a new discovered family of Fe-based high temperature superconductors (HTS) . These systems are made of iron chalcogenide FeSe molecular layers, intercalated by A=K,Cs,Rb,Tl, (Tl,Rb), (Tl,K) spacer layers, providing the more recent practical realization of metal heterostructures at atomic limit, as cuprates and pnictides high temperature superconductors. These chalcogenide superconductors show both high temperature superconductivity and magnetism. In these compounds, one may tune the interplay of superconductivity and magnetism by changing the Fe-vacancy order and the superlattice misfit strain. The open question answered in this thesis is whether there is a co-existence of magnetism and superconductivity in the same spatial region or these phenomena occur in different spatial regions dictated by the phase separation.
In order to understand the complex behaviour of superconductors and to answer this key question, advanced synchrotron radiation focusing down to a size of 300 nm has been used to visualize nanoscale phase separation in the superconducting system using scanning nano-focus single crystal X-ray diffraction. The results show an intrinsic phase separation in single crystals at T 520 K, revealing coesistance of; i) a magnetic phase characterized by an expanded lattice with superstructures due to Fe vacancy ordering and; ii) a non-magnetic phase with an in-plane compressed lattice. The spatial distribution of the two phases at 300 K shows a frustrated or arrested nature of the phase separation. The space resolved imaging of the phase separation permitted us to provide a direct evidence of nano phase domains smaller than 300 nm and different micron size regions with percolating magnetic or non-magnetic domains forming a multiscale complex network of the two phases.
The phase separation appears on multiple scales from micron-scale to nano-scale in cuprates, diborides and pnictides. Several theories have described the complex phase separation as an intrinsic feature of all known HTS.
The multilayer architecture, a common feature of cuprates, diborides, pnictides and chalcogenides, underlines the relevance of lattice effects for high-temperature superconductivity. The structure of the iron pnictide superconductors is made of a superlattice of with Q = 1, layers intercalated by spacers (oxide layers like or in the “1111” family or metallic atomic layers in the “122” family, and therefore they represent practical realizations of a ‘heterostructure at the atomic limit’ (HsAL) that was described to be the essential material architecture for the emergence of HTS. All of them contain a characteristic layer of FeAs layers made of a tetrahedral network (with As atoms located at the apical sites of the tetrahedron) corresponding to the featured planar plane in cuprates and honey-comb 2D lattice of boron in diborides. In pnictides and chalcogenides, EXAFS and XANES measurements have shown the local lattice fluctuations like in cuprates.
These results have recently been applied to design a new heterostructure at the atomic limit for functional materials.
Infact, at the end of this thesis we propose a novel class of heterostructures made of alternate layers of pnictides and cuprates to produce an High-Temperature multiband Superconductor (HTMS) material which have additional microscopic degrees of freedom. These HTMS are multilayers involving alternate layer components from cuprate and iron-arsenide superconductor families. In particular, we provide a specific example of a composite system involving two basic components, and NdOFeAs. The idea of such a HTMS is motivated by the striking similarities in the structural and electronic (as evidenced by the Nd -XANES) properties of the and NdOFeAs systems. The
electronic properties and the XANES calculations for this novel HTMS are presented to highlight the importance of such a superstructure which offers further scope for the material manipulation and design of high temperature superconductors
MATERIALI ELETTRODICI PER LO SVILUPPO DI SENSORI E BIOSENSORI DI INTERESSE BIOLOGICO E ALIMENTARE
No full textSelenoproteins in mammalian spermatogenesis:role of the nuclear GPx4
No full textThe selenoprotein Phospholipid Hydroperoxide Glutathione Peroxidase (PHGPx/GPx4) is an enzyme unique among the various GPxs, because it is able to use protein thiols, beside glutathione, The GPx4 gene encodes for three isoforms having different subcellular localization, being located in the mitochondria (mGPx4), in the cytosol (cGPx4) and in the nucleus (nGPx4), each having distinct functions. The mGPx4 is important to male fertility, as proven by the structural abnormalities of sperm tails from KO mice specifically lacking this isoform, which make these mutants infertile. As for the nuclear isoform, nGPx4-KO mice are fertile but show impaired nuclear condensation of sperm isolated from the caput epididymis, suggesting a role in chromatin stability. To gain more insight into the functions of nGPx4, we first investigated the subnuclear localization of this form in both COS-1 cells overexpressing nGPx4 and mouse male germ cells at different steps of maturation (round spermatids and epididymal spermatozoa). We performed both biochemical and morphological analyses and found that nGPx4 was localized at the level of the nuclear matrix. To test the functional role in chromatin dynamics sperm isolated from the caput and the cauda epididymides from WT and nGPx4-KO mice were subjected to an in vitro chromatin decondensation assay. Our results show that nGPx4-KO mice sperm decondensed earlier than those from WT at all stages of epididymal maturation, providing conclusive evidence that nGPx4 is required for a correct sperm chromatin remodelling. We next addressed the issue whether the sperm nuclear structure instability caused by the lack of nGPx4 might impact on the early events occurring after fertilization. In "in vitro" fertilization experiments, we revealed that, compared to WT, nGPx4-KO mice showed an acceleration of sperm nuclear decondensation, confirming the results previously obtained
La tutela penale della salute e della sicurezza nei luoghi di lavoro
No full textNella prima parte del lavoro sono state esaminate le figure soggettive su cui grava il c.d. obbligo prevenzionistico. Si è ritenuto opportuno premettere talune considerazioni in tema di reato proprio sul rilievo che, in determinati settori, ivi compreso quello oggetto di analisi, l’identificazione della lesione penalmente rilevante si interseca con vincoli funzionali riferibili a specifiche categorie soggettive e con esigenze, altrettanto funzionali, di salvaguardia di interessi particolari. Nel secondo capitolo è stato affrontato il tema del trasferimento di funzioni che ha trovato formale riconoscimento nell’art. 16 D.lgs n. 81/08. Sono stati quindi esaminati gli illeciti penali (codicistici ed extra-codicistici) nell’ambito c.d. antinfortunistico. Da ultimo, si è passato alla trattazione, per gli aspetti d’interesse, della disciplina sulla responsabilità da reato degli enti
The non-gravitational accelerations of the Cassini spacecraft and the nature of the Pioneer anomaly
No full textSTUDIO ANALITICO DEI COMPLESSI CULTUALI DELLA SARDEGNA PROTOSTORICA
No full textNuragic sanctuaries represent the most consistent expression of ritual behaviour in Western Mediterranean during the whole European Protohistory. The research follows a general scheme which proceeds from punctual archaeological analyses and gradually reaches wider degrees of comparative considerations. The study starts with an exhaustive chronological revision of the whole evidence related to Nuragic ritual practices, thus including proper sanctuaries, hoards and isolated offerings. All the collected evidence is then employed in a functional analysis, which aims to the recognition of the individual ritual behaviour as it is determined by commonly shared norms, ensuing from the social environment. In the latter chapters the impact of nuragic sanctuaries in the socio-political reltionships among Nuragic communities is finally explored. The rise of vast monumental stone-built sanctuaries bears evidence of the effective capacity of nuragic communities - which are scattered among thousands of limited size settlements in a relatively small territory - of gathering and employing large amounts of manpower and skilled labour. Nuragic sanctuaries are the fulcrum of religious and socio-political relationships inside and between Sardinian communities during the Late Bronze Age and the Early Iron Age, leading to the formation of broad sub-regional political entities which are capable to interact, on a fair basis, with the protourban Villanovian communities and the early Phoenician colonies. The study is partly based upon the consistent, and fully unpublished, evidence from Monte S. Antonio di Siligo (SS), one of the largest Sardinian sanctuaries
