122,606 research outputs found
Kinetic models for systems of interacting agents with multiple microscopic states
No full textWe propose and investigate general kinetic models with transition probabilities that can describe the simultaneous change of multiple microscopic states of the interacting agents. These models can be applied to many problems in socio-economic sciences, where individuals may change both their compartment and their characteristic microscopic variable, as for instance kinetic models for epidemic diffusion or for international trade with possible transfers of agents. Mathematical properties of the kinetic model are proved, as existence and uniqueness of a solution for the Cauchy problem in suitable Wasserstein spaces. The quasi-invariant asymptotic regime, leading to simpler kinetic Fokker-Planck-type equations, is investigated and commented on in comparison with other existing models. Some numerical tests are performed in order to show the time evolution of distribution functions and of meaningful macroscopic fields, even in case of non-constant interaction rates and transfer probabilities
Chemical bonding and properties of Condensed Phases of Carbon and Silicon
No full textsp3 hybrids plus a linear combination of atomic orbitals description of the Si -Si “bond density” are shown to explain quantitatively both the measured X-ray and the electron scattering intensities from amorphous Si, when combined with a random network model of structure. Appealing to results from computer simulation, amorphous Si is then compared and contrasted with liquid Si. Amorphous carbon is also considered, first from the point of view of the admixture of sp3 and sp’ hybrids and then again in relation to the liquid phase of C. Some surface properties of crystalline Si are then treated using chemical bonding models. Porous Si is also considered, the relation to bonding and surface properties, with the additional factor of quantum confinement being discussed. Finally, some results are presented for small-angle X-ray scattering based on a vacancy model of porous S
Atomic intermixing and electronic interaction at the Pd - Si (111) interface
No full textWe present a theoretical study of electronic properties of the Pd-Si(111) interface in the early stages of interaction. Three models are considered: a chemisorbed Pd layer on Si, an epitaxial Pd2Si layer on Si, and a near-surface Si layer containing interstitial Pd atoms. By comparing the results of our calculations with the spectroscopic data, we find that the model of mixing interstitial Pd atoms in Si is the most appropriate one. This suggests an interpretation of the interfacial reaction in terms of a precursor state of formation of Pd silicide
Covid-19 and ENT practice: Our experience: ENT outpatient department, ward and operating room management during the SARS-CoV-2 pandemic
No full textCoronavirus COVID-19 SARS-CoV-2 ENT Otolaryngolog
n‑BiSI Thin Films: Selenium Doping and Solar Cell Behavior
No full textBiSI (indirect band gap = 1.57 eV) is a recently discovered
photoelectrode
material possessing promising optical properties for use in alternative
thin film solar cells. In this work, we study the effects of selenium
doping on BiSI film properties and also demonstrate the incorporation
of BiS1–xSexI films into both electrochemical and solid state solar cells.
Tuning the band gap of BiS1–xSexI by substituting selenium for sulfur was
accomplished by substituting various amounts of SeO2 for
thiourea in the BiSI spray pyrolysis precursor solutions. This strategy
was employed to reduce the direct band gap of BiS1–xSexI films from 1.63
eV to as low as 1.48 eV, as measured by UV–vis–NIR diffuse
reflectance spectroscopy for x = 0.4. Both electrochemical
and solid state solar cell devices utilizing n-BiSI as the light absorbing
material demonstrated open circuit voltages of nearly 0.4 V. The electrochemical
devices showed much higher short circuit currents and power conversion
efficiencies than the solid state devices. Power conversion efficiencies
of up to 0.25 and 0.012% were measured for electrochemical and solid
state devices, respectively, under AM1.5G illumination
On commuting polynomial automorphisms of C2
No full textWe characterize the commuting polynomial automorphisms of C2, using their meromorphic extension to P2 and looking at their dynamics on the line at infinity
Electrical transport properties of V3Si, V5Si3 and VSi2 thin films
No full textResistivity measurements in a wide temperature range (2–1100 K) have been performed on thin films of V3Si, V5Si3, and VSi2 formed on an inert substrate. An anomalous resistivity behavior has been observed in these metallic compounds: The resistivity deviates from linearity and approaches a saturation value at the higher temperatures. The resistivity data can be fitted quite well to a phenomenological expression based on the idea that a limiting resistivity is reached when the electron mean free path is of the order of the interatomic spacing. The electron mean free paths, which have been computed from the experimental data, lend support to the above idea. The saturation phenomenon in V3Si and V5Si3 compounds is characterized by a limiting resistivity of the same magnitude as observed in several A15 materials and in the Mooij correlation, yet in VSi2 the resistivity saturates to a much higher value. The V3Si is a superconductor with a transition temperature around 15 K and a residual resistivity ratio of 10.6. On the other hand, V5Si3 and VSi2 thin compound films do not show superconductivity state down to 2 K. The temperature dependence of the Hall coefficient gives evidence of a complex and different electronic structure of the three compounds
Early Diagnosis of Neurodegenerative Diseases: What Has Been Undertaken to Promote the Transition from PET to Fluorescence Tracers
No full textAlzheimer's Disease (AD) and Parkinson's Disease (PD) represent two among the most frequent neurodegenerative diseases worldwide. A common hallmark of these pathologies is the misfolding and consequent aggregation of amyloid proteins into soluble oligomers and insoluble beta-sheet-rich fibrils, which ultimately lead to neurotoxicity and cell death. After a hundred years of research on the subject, this is the only reliable histopathological feature in our hands. Since AD and PD are diagnosed only once neuronal death and the first symptoms have appeared, the early detection of these diseases is currently impossible. At present, there is no effective drug available, and patients are left with symptomatic and inconclusive therapies. Several reasons could be associated with the lack of effective therapeutic treatments. One of the most important factors is the lack of selective probes capable of detecting, as early as possible, the most toxic amyloid species involved in the onset of these pathologies. In this regard, chemical probes able to detect and distinguish among different amyloid aggregates are urgently needed. In this article, we will review and put into perspective results from ex vivo and in vivo studies performed on compounds specifically interacting with such early species. Following a general overview on the three different amyloid proteins leading to insoluble beta-sheet-rich amyloid deposits (amyloid beta(1-42) peptide, Tau, and alpha-synuclein), a list of the advantages and disadvantages of the approaches employed to date is discussed, with particular attention paid to the translation of fluorescence imaging into clinical applications. Furthermore, we also discuss how the progress achieved in detecting the amyloids of one neurodegenerative disease could be leveraged for research into another amyloidosis. As evidenced by a critical analysis of the state of the art, substantial work still needs to be conducted. Indeed, the early diagnosis of neurodegenerative diseases is a priority, and we believe that this review could be a useful tool for better investigating this field
Linear Fractional Maps of the unit ball: a geometric study.
No full textWe classify up to conjugation with automorphisms the linear fractional self-maps of the unit ball of (n>1). Then we give some applications of these normal forms to the study of composition operators
Photovoltaic Performance of Phase-Pure Orthorhombic BiSI Thin-Films
No full textA single-precursor solution approach is developed for depositing stoichiometric BiSI thin films featuring pure paraelectric orthorhombic (Pnam) phase. The compact and homogeneous films are composed of flake-shaped grains oriented antiplanar to the substrate and display a sharp optical transition corresponding to a bandgap of 1.57 eV. Optical and Raman signatures of the thin films are rationalized using the quasiparticle G 0W 0@PBE0 and density functional perturbation theory calculations. Electrochemical impedance spectroscopy revealed n-type doping with valence and conduction band edges located at 4.6 and 6.2 eV below vacuum level, respectively. Planar BiSI solar cells are fabricated with the architecture: Glass/FTO/SnO 2/BiSI/F8/Au, where F8 is poly(9,9-di-n-octylfluorenyl-2,7-diyl), showing record conversion efficiency of 1.32% under AM 1.5 illumination. </p
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