329 research outputs found
ION BEAM-STIMULATED AUGER-ELECTRON EMISSION FROM CR AND CR-SILICIDES
No full textThe emission of Auger electrons induced by energetic ions impact on Cr and Cr-silicides of different stoichiometry (Cr3Si and CrSi2) was investigated. Attention was focused on the origin, nature and characteristics of the metal peaks and on the role of asymmetric metal-silicon collision for the Cr and Si atom excitation. The ion excited, M23-related, low energy Cr spectrum essentially originates in the decay of slow sputtered Cr atoms. The Cr autoionization satellite almost completely vanishes, while interatomic transitions involving Cr and Ar atoms occur. Cr-Si collisions have been found to be efficient for the ionization of either Si and Cr atoms, indicating that excitation can also occur in the heavier partner
Triode electron bombardment evaporation source for ultrahigh vacuum thin film deposition
No full textA new electron bombardment evaporation source for ultrahigh vacuum (UHV) thin film deposition is presented. It is based on an original electrodes configuration (modeled on that of a vacuum triode) featuring, besides anode and filament, a biased grid acting as a power modulator. The presence of a polarized grid helps to minimize space charge problems, to improve electron focusing and to fine control the dissipation on the evaporating material, governing the sublimation rate. The electrodes geometry was optimized by studying electron trajectories and electrical field distribution in the electrodes zone with ray-tracing analysis. Mechanical solutions and electrodes geometry were designed to ensure low outgassing and UHV compatibility, as well as to facilitate maintenance and source cleaning. The evaporator is water cooled and a mechanically operated shutter is present. The working principles and the technical details are presented together with operating data and evaporation performances
Electronic properties of tetrakis(pentafluorophenyl)porphyrin
No full textWe studied in detail the electronic properties of C44H10F20N4 (tetrakis(pentafluorophenyl)porphyrin, hereafter H2TPP(F)) via a combined study by photoelectron spectroscopy (PES) and density functional (DF) calculations, shedding new light on the role of the halide in this very interesting molecule for organic electronics. Valence and core levels have been investigated by means of PES on H2TPP(F) thin films deposited on the SiO2/Si(100) native oxide surface by supersonic molecular beam deposition (SuMBD). These experiments have been carefully interpreted on the basis of DF results pertaining to the isolated H2TPP(F). Non-relativistic calculations have been run to investigate valence states, whereas a two component relativistic approach within the zeroth-order regular approximation has been adopted to study core levels. The present results, in conjunction with those obtained previously on the H2TPP parent compound [M. Nardi, R. Verucchi, C. Corradi, M. Pola, M. Casarin, A. Vittadini and S. Iannotta, Phys. Chem. Chem. Phys., 2010, 12, 871], pave the way towards designing fully organic p–n junctions by using these macrocycles
Myocardial infarction risk in HIV-infected patients: epidemiology, pathogenesis, and clinical management
No full textHighly active antiretroviral therapy (HAART) has dramatically reduced morbidity and mortality associated with acquired immunodeficiency syndrome (AIDS), and human immunodeficiency virus (HIV) infection has become a chronic and manageable disease. Paralleling increased life expectancy, HIV-infected subjects may present many comorbidities, most notably cardiovascular diseases, and recent studies have identified an increased prevalence of traditional coronary risk factors in these patients. Moreover, additional investigations suggest that HIV itself may independently favour premature atherosclerosis, and antiretroviral agents also could directly or indirectly play a role in the atherosclerotic process. Dyslipidaemia, insulin resistance, inflammation, and fat redistribution are all likely to contribute to this pathogenetic pathway, and these abnormalities may be interrelated and due to either HIV infection, or the related inflammatory syndrome, or HAART-associated toxicity. Appropriate screening and assessment of cardiovascular risk and intensive strategies for prevention of cardiovascular events are suitable in HIV-infected patients, including lifestyle measures, switching antiretroviral drugs, and pharmacologic therapy of lipid and glucose metabolism alterations. This article reviews the correlation between HIV infection and myocardial infarction, and discusses the most appropriate clinical management of cardiovascular risk among HIV-positive individual
Il professionista sanitario in ambito odontostomatologico e l'esposizione al rischio infettivo: epidemiologia e prevenzione
No full textMolecular Doping of CVD-Graphene Surfaces by Perfluoroalkyl-Substituted Perylene Diimides Derivatives
No full textNon-covalent π-π and dipolar interactions with small aromatic molecules have been widely demonstrated to be a valid option to tune graphene work functions without adding extrinsic scattering centers for charge carriers. In this work, we investigated the interaction between a CVD-graphene monolayer and a thermally evaporated sub-monolayer and the following few-layer thin films of similar perylene diimide derivatives: PDI8-CN2 and PDIF-CN2. The molecular influence on the graphene work function was estimated by XPS and UPS analysis and by investigating the surface potentials via scanning Kelvin probe force microscopy. The perfluorinated decoration and the steric interaction in the early stages of the film growth determined a positive work function shift as high as 0.7 eV in the case of PDIF-CN2, with respect to the value of 4.41 eV for the intrinsic graphene. Our results unambiguously highlight the absence of valence band shifts in the UPS analysis, indicating the prevalence of dipolar interactions between the graphene surface and the organic species enhanced by the presence of the fluorine-enriched moieties
Terapia antiretrovirale con inibitori nucleosidici della trascrittasi inversa ed epatotossicità nei pazienti HIV positivi
No full textNucleoside analogue transcriptase inhibitors and liver toxicity among patients treated for hiv disease
No full textGrowth of Fe ultrathin films on Ni(111): structure and electronic properties
No full textWe investigated the evolution during film growth of the electronic properties of Fe/Ni(111) ultrathin films with electron energy loss spectroscopy from the valence band and from the Fe L-2,L-3 ionization edges, relating them with structural modifications monitored with low energy electron diffraction. At ca. 4 monolayers of Fe a fee to bce phase transition was observed with the major changes in the electronic structure occurring in the 3d band region. (C) 2000 Elsevier Science B.V. All rights reserved
Chronic hepatitis with diffuse steatosis and slight fibrosis related to etretinate therapy
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