Generalization of the Eliashberg equations and Density Functional Theory applied to the analysis of the fundamental properties of iron-based superconductors.

Density Functional Theory (DFT) allows a fully ab-initio treatment of almost all the quantities that enter in the Eliashberg theory and in many other approaches used to study both the superconducting and the normal phase. A complete description from first principles of real materials is, al least in principle, possible. Here DFT and Eliashberg theory are applied to the study of some members of the new family of superconductors discovered in 2008, the iron-compounds. Superconductivity here is unconventional and unlikely mediated by phonons. When electronic mechanisms are involved and the properties of the compounds are more complex, as in the case of Fe-based superconductors, also the ab-initio treatment may require some reasonable ad hoc approximations, derived from experimental evidences or theoretical argumentations, introducing some phenomenological aspects in the formulation. In this thesis, Eliashberg theory and DFT are applied to study the properties of some iron compounds, in particular the properties of LiFeAs and Co-doped Ba-122 are discussed both in the normal and in the superconducting state. In order to unveil the the properties of the superconducting state, in particular the symmetry and the amplitude of the order parameter and the coupling mechanism, a four bands Eliashberg model is discussed for LiFeAs suggesting that the specific electronic structure of this peculiar compound may lead to the breakdown of the Migdal's theorem forcing the model to be phenomenological". The relation between the topology of the Fermi surface and the presence of nodes is studied in Point-contact Andreev-reflection spectra of Ba(Fe1-xCox)2As2 (both thin fims and single crystals) and Ca(Fe1-xCox)2As2. The curves presented are fitted within the multiband 3D-BTK model that allows the inclusion of the real shape of the Fermi surface evaluated within DFT. Thanks to the inclusion of the results obtained within the Eliashberg theory in the 2D-BTK model some additional structures due to the strong electron-boson interaction, that appear at energy higher than the amplitude of the gaps in some AR spectra, can be studied and some guesses about the nature of the superconducting mechanism can be made. This technique is here applied to the case of Ba(Fe1-xCox)2As2 thin films with x = 0.08. Finally, as concern the normal state, the temperature dependence of resistivity is reproduced both in LiFeAs and Ba(Fe1-xCox)2As2 with a model that contains two different kind of carriers. For both compounds spin fluctuations play an important role also in the normal state in addition to being the main bosons that mediate the Cooper pairing and in both compound the transport coupling constant results to be sensibly smaller than the superconducting one, suggesting a way to find a unifying principle for HTCS

Resistivity in Co-doped Ba-122: comparison of thin films and single crystals

The temperature dependence of the resistivity of epitaxial Ba(Fe_(1-x)Co_x)2As2 thin films (with nominal doping x = 0.08, 0.10 and 0.15) has been analyzed and compared with analogous measurements on single crystals taken from literature. The rho(T) of thin films looks different from that of single crystals, even when the cobalt content is the same. All rho(T) curves can be fitted by considering an effective two-band model (with holes and electrons bands) in which the electrons are more strongly coupled with the bosons (spin fluctuations) than holes, while the effect of impurities is mainly concentrated in the hole band. Within this model the mediating boson has the same characteristic energy in single crystals and thin films, but the shape of the transport spectral function at low energy has to be very different, leading to a "hardening" of the electron-boson spectral function in thin films, associated with the strain induced by the substrate.Comment: 13 pages, 4 figure

Understanding the potentiality of accelerator based-boron neutron capture therapy for osteosarcoma: Dosimetry assessment based on the reported clinical experience

Background: Osteosarcoma is the most frequent primary malignant bone tumour, and its incidence is higher in children and adolescents, for whom it represents more than 10% of solid cancers. Despite the introduction of adjuvant and neo-adjuvant chemotherapy that markedly increased the success rate in the treatment, aggressive surgery is still needed and a considerable percentage of patients do not survive due to recurrences or early metastases. Boron Neutron Capture Therapy (BNCT), an experimental radiotherapy, was investigated as a treatment that could allow a less aggressive surgery by killing infiltrated tumour cells in the surrounding healthy tissues. BNCT requires an intense neutron beam to ensure irradiation times of the order of 1h. In Italy, a Radio Frequency Quadrupole (RFQ) proton accelerator has been designed and constructed for BNCT, and a suitable neutron spectrum was tailored by means of Monte Carlo calculations. This paper explores the feasibility of BNCT to treat osteosarcoma using this neutron source based on accelerator. Methods: The therapeutic efficacy of BNCT was analysed evaluating the dose distribution obtained in a clinical case of femur osteosarcoma. Mixed field dosimetry was assessed with two different formalisms whose parameters were specifically derived from radiobiological experiments involving in vitro UMR-106 osteosarcoma cell survival assays and boron concentration assessments in an animal model of osteosarcoma. A clinical case of skull osteosarcoma treated with BNCT in Japan was re-evaluated from the point of view of dose calculation and used as a reference for comparison. Results: The results in the case of femur osteosarcoma show that the RFQ beam would ensure a suitable tumour dose painting in a total irradiation time of less than an hour. Comparing the dosimetry between the analysed case and the treated patient in Japan it turns out that doses obtained in the femur tumour are at least as good as the ones delivered in the skull osteosarcoma. The same is concluded when the comparison is carried out taking into account osteosarcoma irradiations with photon radiation therapy. Conclusions: The possibility to apply BNCT to osteosarcoma would allow a multimodal treatment consisting in neo-adjuvant chemotherapy, high-LET selective radiation treatment and a more conservative surgery.Fil: Bortolussi, Silva. University of Pavia; ItaliaFil: Postuma, Ian. University of Pavia; ItaliaFil: Protti, Nicoletta. University of Pavia; ItaliaFil: Provenzano, Lucas. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica; ArgentinaFil: Ferrari, Cinzia. University of Pavia; ItaliaFil: Cansolino, Laura. University of Pavia; ItaliaFil: Dionigi, Paolo. University of Pavia; ItaliaFil: Galasso, Olimpio. University of Catanzaro; ItaliaFil: Gasparini, Giorgio. University of Catanzaro; ItaliaFil: Altieri, Saverio. University of Pavia; ItaliaFil: Miyatake, Shin Ichi. Osaka Medical College; JapónFil: González, Sara Josefina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica; Argentin

Notulae to the Italian alien vascular flora 6

In this contribution, new data concerning the distribution of vascular flora alien to Italy are presented. It includes new records, confirmations, exclusions, and status changes for Italy or for Italian administrative regions of taxa in the genera Acalypha, Acer, Canna, Cardamine, Cedrus, Chlorophytum, Citrus, Cyperus, Epilobium, Eucalyptus, Euphorbia, Gamochaeta, Hesperocyparis, Heteranthera, Lemna, Ligustrum, Lycium, Nassella, Nothoscordum, Oenothera, Osteospermum, Paspalum, Pontederia, Romulea, Rudbeckia, Salvia, Sesbania, Setaria, Sicyos, Styphnolobium, Symphyotrichum, and Tradescantia. Nomenclature and distribution updates, published elsewhere, and corrigenda are provided as supplementary material

Notulae to the Italian native vascular flora: 8

In this contribution, new data concerning the distribution of native vascular flora in Italy are presented. It includes new records, confirmations, exclusions, and status changes to the Italian administrative regions for taxa in the genera Ajuga, Chamaemelum, Clematis, Convolvulus, Cytisus, Deschampsia, Eleocharis, Epipactis, Euphorbia, Groenlandia, Hedera, Hieracium, Hydrocharis, Jacobaea, Juncus, Klasea, Lagurus, Leersia, Linum, Nerium, Onopordum, Persicaria, Phlomis, Polypogon, Potamogeton, Securigera, Sedum, Soleirolia, Stachys, Umbilicus, Valerianella, and Vinca. Nomenclatural and distribution updates, published elsewhere, and corrigenda are provided as Suppl. material 1

Notulae to the Italian alien vascular flora: 12

In this contribution, new data concerning the distribution of vascular flora alien to Italy are presented. It includes new records, confirmations, exclusions, and status changes for Italy or for Italian administrative regions. Nomenclatural and distribution updates published elsewhere are provided as Suppl. material 1

Notulae to the Italian alien vascular flora: 11

In this contribution, new data concerning the distribution of vascular flora alien to Italy are presented. It includes new records, confirmations, exclusions, and status changes for Italy or for Italian administrative regions. Nomenclatural and distribution updates published elsewhere are provided as Suppl. material 1

Carriers of ADAMTS13 Rare Variants Are at High Risk of Life-Threatening COVID-19

Thrombosis of small and large vessels is reported as a key player in COVID-19 severity. However, host genetic determinants of this susceptibility are still unclear. Congenital Thrombotic Thrombocytopenic Purpura is a severe autosomal recessive disorder characterized by uncleaved ultra-large vWF and thrombotic microangiopathy, frequently triggered by infections. Carriers are reported to be asymptomatic. Exome analysis of about 3000 SARS-CoV-2 infected subjects of different severities, belonging to the GEN-COVID cohort, revealed the specific role of vWF cleaving enzyme ADAMTS13 (A disintegrin-like and metalloprotease with thrombospondin type 1 motif, 13). We report here that ultra-rare variants in a heterozygous state lead to a rare form of COVID-19 characterized by hyper-inflammation signs, which segregates in families as an autosomal dominant disorder conditioned by SARS-CoV-2 infection, sex, and age. This has clinical relevance due to the availability of drugs such as Caplacizumab, which inhibits vWF-platelet interaction, and Crizanlizumab, which, by inhibiting P-selectin binding to its ligands, prevents leukocyte recruitment and platelet aggregation at the site of vascular damage