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613 results on '"Privitera, V"'

3. Insulator-metal transition in biased finite polyyne systems

Author

La Magna, A., Deretzis, I., and Privitera, V.

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics, Condensed Matter - Materials Science
Abstract

A method for the study of the electronic transport in strongly coupled electron-phonon systems is formalized and applied to a model of polyyne chains biased through metallic Au leads. We derive a stationary non equilibrium polaronic theory in the general framework of a variational formulation. The numerical procedure we propose can be readily applied if the electron-phonon interaction in the device hamiltonian can be approximated as an effective single particle electron hamiltonian. Using this approach, we predict that finite polyyne chains should manifest an insulator-metal transition driven by the non-equilibrium charging which inhibits the Peierls instability characterizing the equilibrium state., Comment: to appear at EPJB

Published
2009
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24. Simultaneous catalyst deposition and growth of aligned carbon nanotubes on Si[O.sub.2]/Si substrates by radio frequency magnetron sputtering

Author

Scalese, S., Scuderi, V., Privitera, V., Pennisi, A., and Simone, F.

Subjects
Physics
Abstract

Radio frequency magnetron sputtering is used for preparing aligned carbon nanotubes (CNTs) on a Si[O.sub.2]/Si substrate, with simultaneous in situ catalyst deposition. The structural differences are attributed to the size of the W and Ni particles and also to a different diffusion behavior of C in the two kinds of metallic clusters.

Published
2007

28. Magnetic Characterization of Permalloy Nanodome Surfaces on Flexible PEEK/TiO2 Vertical Nanotubes Composites

Author

Martin-Rubio, C., Rivelles, A., Schneider, M., Hoyo, J. C. del, Privitera, V., Worgull, M., Maicas, M., and Sanz, R.

Abstract

Poly-ether-ether-ketone (PEEK) composites present outstanding physical and chemical properties, including radiation tolerance and compatibility with vacuum and additive manufacturing processing. Applications of PEEK range from biomedical to aerospace. Controlled 3-D nanostructuring arises as a powerful approach to generate new phenomena suitable for technological applications. In this sense, we target to synthesize robust and shapeable magnetic nanocomposites (NCs) for sensing and electromagnetic shielding applications. For this aim, we synthesized and characterized Permalloy (Py, Ni80Fe20) nanostructured surfaces on PEEK/TiO2. These NCs were synthesized by scalable and high throughput compatible fabrication approaches: anodization (TiO2 nanotubes) and hot embossing (thermal nanoimprint). The resulting NCs are shapeable, stable below 300 °C, and vacuum compatible. Their surfaces compose TiO2 nanodomes filled by PEEK. Py layers (15 nm) were sputtered on NC and flat PEEK films. The characterization included SEM, AFM, ISO-2409 Adhesion Tests, hysteresis loops, and first-order reversal curves (FORCs). The results revealed that both types of films keep stable characteristics after bending cycles, and noticeable modifications of the magnetic global response and local interactions generated due to the 3-D nanostructure.

Published
2023
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29. Measuring fusion excitation functions with RIBs using the stacked target technique: Problems and possible solutions

Author

Fisichella M., Shotter A. C., Di Pietro A., Figuera P., Lattuada M., Marchetta C., Privitera V., Romano L., Ruiz C., and Zadro M.

Subjects
Physics, QC1-999
Abstract

For measuring fusion excitation functions, the activation technique with a stack of targets offers the considerable advantage that several reaction energies may be simultaneously measured by using one beam energy. However, its main drawback is the degradation of the beam quality as it passes through the stack due to statistical nature of energy loss processes and any non-uniformity of the stacked targets. If not taken properly into account, this degradation can lead to a wrong determination of the fusion excitation function. In this contribution some results of the investigation of this problem are reported.

Published
2016
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34. An investigation on the modeling of transient enhanced diffusion of ultralow energy implanted boron in silicon

Author

Mannino, G., Whelan, S., Schroer, E., Privitera, V., Leveque, P., Svensson, B.G., and Napolitani, E.

Subjects
Boron -- Research, Physics -- Research, Semiconductor doping -- Research, Semiconductors -- Diffusion, Physics
Abstract

Research describing the diffusion of boron in silicon after ultralow energy implantation is presented. Diffusion models based on cluster evolution and the kick-out model are investigated.

Published
2001

44. The prognostic role of FDG PET/CT before combined radio-chemotherapy in anal cancer patients

Author

Leccisotti, Lucia, Manfrida, Stefania, Barone, R., Ripani, Daria, Tagliaferri, L., Masiello, V., Privitera, Vanessa Eugenia, Gambacorta, Maria Antonietta, Rufini, Vittoria, Valentini, Vincenzo, Giordano, Alessandro, Leccisotti L. (ORCID:0000-0002-6000-2898), Manfrida S., Ripani D., Privitera V., Gambacorta M. A. (ORCID:0000-0001-5455-8737), Rufini V. (ORCID:0000-0002-2052-8078), Valentini V. (ORCID:0000-0003-4637-6487), Giordano A. (ORCID:0000-0002-6978-0880), Leccisotti, Lucia, Manfrida, Stefania, Barone, R., Ripani, Daria, Tagliaferri, L., Masiello, V., Privitera, Vanessa Eugenia, Gambacorta, Maria Antonietta, Rufini, Vittoria, Valentini, Vincenzo, Giordano, Alessandro, Leccisotti L. (ORCID:0000-0002-6000-2898), Manfrida S., Ripani D., Privitera V., Gambacorta M. A. (ORCID:0000-0001-5455-8737), Rufini V. (ORCID:0000-0002-2052-8078), Valentini V. (ORCID:0000-0003-4637-6487), and Giordano A. (ORCID:0000-0002-6978-0880)

Abstract

Objective: We assessed the prognostic value of several FDG PET/CT parameters, measured within the primary tumor and the involved lymph nodes, before definitive radio-chemotherapy (RCT) in anal cancer patients. Methods: Anal cancer patients with positive baseline FDG PET/CT who underwent definitive RCT from May 2011 to February 2018 were retrospectively assessed. Primary tumour (T)-SUVmax, T-SUVpeak, T-SUVmean, T-MTV, T-TLG, whole-body (WB) MTV, and WB-TLG were measured. Kaplan–Meier curves, Cox-regression analysis, and logistic regression machine-learning technique were used to test for associations between clinical data, metabolic parameters, and outcomes as overall survival (OS), disease-specific survival (DSS), metastatic-free survival (MFS), disease-free survival (DFS), local relapse-free survival (LRFS), and colostomy-free survival (CFS). Results: Fifty-nine patients were included in the study. Median follow-up was 28 months. Higher pre-treatment WB-MTV, T-TLG, and WB-TLG were associated with worse OS (p = 0.025, 0.021, and 0.02, respectively). PET parameters resulted also statistically significant for DSS, DFS, and CFS (p = 0.032, 0.043, 9 × 10−4 for WB-TLG). Cox analysis showed that PET parameters are significant predictors of OS, DSS, DFS, CFS, and LRFS. On multivariate analysis, age, stage, T-SUVpeak, WB-MTV, and T-TLG resulted significantly related to OS. A further stratification for patients with advanced stage (cT3-4 any N or any cT, N +) showed that MTV and TLG, measured within the primary tumor and the involved nodes, are significantly higher in patients with a worse prognosis. In this subgroup, cut-off values of T- and WB-TLG as well as T- and WB-MTV showed a statistically significant correlation with clinical outcomes. Conclusions: Pre-treatment metabolic parameters measured within the primary tumor and the involved nodes may represent additional new biomarkers for estimating prognosis in anal cancer patients, especially in advanced stage patien

Published
2020

45. Power bipolar transistors with a fast recovery integrated diode

Author

Coffa, S., Magri, A., Frisina, F., and Privitera, V.

Subjects
Bipolar transistors -- Models, Diodes -- Usage, Business, Electronics, Electronics and electrical industries
Abstract

A high voltage power bipolar transistor with an integrated fast recovery diode is used in power devices. The diode is connected between the transistor's emitter and collector. The diode's switching speed can be increased by localized Pt doping, followed by a thermal process to limit the lateral diffusion of metal atoms. The transistor's current carrying capacity is minimally reduced on increasing the switching speed.

Published
1996

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