83 research outputs found
Promising Perspectives on the Use of Fullerenes as Efficient Containers for Beryllium Atoms
The possibility of using fullerenes as containers for toxic beryllium atoms is studied by a multi-scale approach in which first-principles and classical molecular dynamics simulations are combined. By studying the energetics, electronic and spectroscopic properties of Be-fullerene systems and by simulating their interaction at finite temperature in vacuo and in representative biological environments it is concluded that: i) Be endohedral complexes can be obtained by implanting Be atoms at energies >2.3 eV that is consistent with laser implantation technologies; ii) it is in principle possible to distinguish stable endohedral complexes from metastable exohedral ones by optical absorption, suggesting that optical spectroscopy can be a valuable a non-destructive technique to assist the synthesis and the control of implanted films iii) the Be-endohedral complexes are long-lived and thermodynamically stable and can confine beryllium both in vacuo and in aqueous solution; iv) Be@C60 complexes are likely unable to penetrate the selectivity filters of a prototypical protein showing that fullerene prevents undesired interactions with biomolecules and toxicity effects of Be2+ related to replacement of the Ca2+. Overall, these results provide an assessment on the possibility to encapsulate Be atoms into fullerenes by ion implantation to synthesize inert and highly stable and safe molecular containers for toxic beryllium radionuclides. Great opportunities are expected for the realization and application of Be-C60 complexes to nanotechnology and nanomedicine with particularly appealing perspectives in the field of neutron capture therapy of cancer
Dynamic Local Structure in Caesium Lead Iodide: Spatial Correlation and Transient Domains
Metal halide perovskites are multifunctional semiconductors with tunable
structures and properties. They are highly dynamic crystals with complex
octahedral tilting patterns and strongly anharmonic atomic behaviour. In the
higher temperature, higher symmetry phases of these materials, several complex
structural features have been observed. The local structure can differ greatly
from the average structure and there is evidence that dynamic two-dimensional
structures of correlated octahedral motion form. An understanding of the
underlying complex atomistic dynamics is, however, still lacking. In this work,
the local structure of the inorganic perovskite CsPbI is investigated using
a new machine learning force field based on the atomic cluster expansion
framework. Through analysis of the temporal and spatial correlation observed
during large-scale simulations, we reveal that the low frequency motion of
octahedral tilts implies a double-well effective potential landscape, even well
into the cubic phase. Moreover, dynamic local regions of lower symmetry are
present within both higher symmetry phases. These regions are planar and we
report the length and timescales of the motion. Finally, we investigate and
visualise the spatial arrangement of these features and their interactions,
providing a comprehensive picture of local structure in the higher symmetry
phases
Radiomic Features from Post-Operative 18F-FDG PET/CT and CT Imaging Associated with Locally Recurrent Rectal Cancer: Preliminary Findings
Locally Recurrent Rectal Cancer (LRRC) remains a major clinical concern, it rapidly invades
pelvic organs and nerve roots, causing severe symptoms. Curative-intent salvage therapy offers the only potential for cure but it has a higher chance of success when LRRC is diagnosed at an early stage. Imaging diagnosis of LRRC is very challenging due to fibrosis and inflammatory pelvic tissue which can mislead even the most expert reader. This study exploited a radiomic analysis to enrich, through quantitative features, the characterization of tissue properties, thus favouring an accurate detection of LRRC by Computed Tomography (CT) and 18F-FDG-Positron Emission Tomography/CT (PET/CT).
Of 563 eligible patients, undergoing radical resection (R0) of primary RC, 57 patients with suspected LRRC were included, 33 of which histologically confirmed. After manually segmenting suspected LRRC in CT and PET/CT, 144 radiomic features (RFs) were generated, and RFs were investigated for univariate significant discriminations (Wilcoxon rank-sum test, p<0.050) of LRRC from NO LRRC. Five RFs in PET/CT (p<0.017) and 2 in CT (p<0.022) enabled, individually, a clear distinction of the groups, and one RF was shared by PET/CT and CT. Besides confirming the potential role of radiomics to advance LRRC diagnosis, the aforementioned shared RF describes LRRC as tissues having high local inhomogeneity due to evolving tissueâs properties
UNITO E LâAFRICA. Progetti, iniziative, relazioni per una strategia di Ateneo
Questo documento raccoglie gli esiti di un percorso avviato quasi due anni fa, con una prima richiesta di segnalazione di progetti volta a costruire una mappatura di iniziative in, per e con attori e territori africani che coinvolgevano in vari modi lâAteneo, con le sue strutture e personale, tra ricerca, didattica, terza missione e cooperazione allo sviluppo
Ion MigrationâInduced Amorphization and Phase Segregation as a Degradation Mechanism in Planar Perovskite Solar Cells
The operation of halide perovskite optoelectronic devices, including solar cells and LEDs, is strongly influenced by the mobility of ions comprising the crystal structure. This peculiarity is particularly true when considering the longâterm stability of devices. A detailed understanding of the ion migrationâdriven degradation pathways is critical to design effective stabilization strategies. Nonetheless, despite substantial research in this first decade of perovskite photovoltaics, the longâterm effects of ion migration remain elusive due to the complex chemistry of lead halide perovskites. By linking materials chemistry to device optoelectronics, this study highlights that electrical biasâinduced perovskite amorphization and phase segregation is a crucial degradation mechanism in planar mixed halide perovskite solar cells. Depending on the biasing potential and the injected charge, halide segregation occurs, forming crystalline iodideârich domains, which govern light emission and participate in light absorption and photocurrent generation. Additionally, the loss of crystallinity limits charge collection efficiency and eventually degrades the device performance
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