Venezia, Italy
Venezia, Italy

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Cazzanelli M.,University of Trento | Bianco F.,University of Trento | Borga E.,University of Trento | Pucker G.,Advanced Photonics and Photovoltaics Unit | And 9 more authors.
Nature Materials | Year: 2012

Silicon photonics meets the electronics requirement of increased speed and bandwidth with on-chip optical networks. All-optical data management requires nonlinear silicon photonics. In silicon only third-order optical nonlinearities are present owing to its crystalline inversion symmetry. Introducing a second-order nonlinearity into silicon photonics by proper material engineering would be highly desirable. It would enable devices for wideband wavelength conversion operating at relatively low optical powers. Here we show that a sizeable second-order nonlinearity at optical wavelengths is induced in a silicon waveguide by using a stressing silicon nitride overlayer. We carried out second-harmonic-generation experiments and first-principle calculations, which both yield large values of strain-induced bulk second-order nonlinear susceptibility, up to 40 pm V -1 at 2,300 nm. We envisage that nonlinear strained silicon could provide a competing platform for a new class of integrated light sources spanning the near-to mid-infrared spectrum from 1.2 to 10μm. © 2012 Macmillan Publishers Limited. All rights reserved.


Alonso U.,CIEMAT | Missana T.,CIEMAT | Garcia-Gutierrez M.,CIEMAT | Patelli A.,CIVEN | And 2 more authors.
Physics and Chemistry of the Earth | Year: 2011

An experimental methodology applying the nuclear ion beam technique Rutherford Backscattering Spectrometry (RBS) is used to measure colloid diffusion profiles within three different types of clay: consolidated Opalinus clay (Switzerland), Callovo-Oxfordian clay (France) and FEBEX bentonite (Spain) compacted at different densities. The RBS technique is widely applied in materials science and it was selected because it allows the measurement of concentration profiles at short range distances (μm). The effects of colloid size, clay type and clay density were analyzed with negatively charged Au colloids of 2, 20 and 40. nm. Apparent diffusion coefficients (Da) for gold colloids could be measured and Da values ranged from (10-18 to 10-19m2/s). The larger diffusion coefficient was measured for 2nm colloids in the Opalinus clay with Da(Au 2nm)=(2.1±0.5)×10-18m2/s. The accessible porosity for colloids is even lower than that measured for anions, since not only anion exclusion but also size exclusion hinders diffusion. For example, 40nm colloids did not accede at all to bentonite compacted at higher densities. © 2011 Elsevier Ltd.


Mardegan A.,University of Venice | Scopece P.,CIVEN | Lamberti F.,University of Padua | Meneghetti M.,University of Padua | And 2 more authors.
Electroanalysis | Year: 2012

The results of a study on the determination of trace levels of arsenic with nanoelectrode ensembles (NEEs) are reported. In order to lower the detection limit and to increase the number of performable analysis for each NEE, the right choice of the supporting electrolyte concentration and electroanalytical parameters were optimized. The electrochemical behavior of As(III) at NEEs was studied at first by cyclic voltammetry, while trace concentrations of As(III) were determined by anodic stripping square wave voltammetry. The method is characterized by a detection limit as low as 5ng/L (65 pM) after 3min preconcentration at -0.4V. Finally, NEEs were applied to trace As analysis in real samples such as certified seawater samples. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Mardegan A.,University of Venice | Dal Borgo S.,Slovenian National Institute of Chemistry | Scopece P.,CIVEN | Moretto L.M.,University of Venice | And 2 more authors.
Electrochemistry Communications | Year: 2012

The preparation of bismuth modified ensembles of gold nanoelectrodes (Bi-NEE) is described for the first time. Bi-NEEs are characterized and successfully applied for anodic stripping voltammetric measurement of trace Pb(II). Optimization of the experimental parameters provided low detection limits of 60 ng L - 1 and 30 ng L - 1 by using in-situ and ex-situ bismuth film deposition, respectively, after a 3 min accumulation step. © 2012 Elsevier B.V.


Mardegan A.,University of Venice | DalBorgo S.,Slovenian National Institute of Chemistry | Scopece P.,CIVEN | Moretto L.M.,University of Venice | And 2 more authors.
Electroanalysis | Year: 2013

A study on the simultaneous determination of Ni(II) and Co(II) dimethylglyoximates (Ni-DMG and Co-DMG) through adsorptive cathodic stripping voltammetry at an in situ bismuth-modified gold electrode (Bi-AuE) is reported. The key operational parameters, such as Bi(III) concentration, accumulation potential and accumulation time were optimized and the morphology of the Bi-microcrystals deposited on the Au-electrode was studied. The Bi-AuE allowed convenient analysis of trace concentrations of solely Ni(II) or of Ni(II) and Co(II) together, with cathodic stripping voltammograms characterized by well-separated stripping peaks. The calculated limit of detection (LOD) was 40ngL-1 for Ni(II) alone, whereas the LOD was 98ngL-1 for Ni(II) and 58ngL-1 for Co(II), when both metal ions were measured together. The optimized method was finally applied to the analysis of certified spring water (NIST1640a) and of natural water sampled in the Lagoon of Venice. The results obtained with the Bi-AuE were in satisfactory agreement with the certified values and with those provided by complementary techniques, i.e., ICP-OES and ICP-MS. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Mardegan A.,University of Venice | Scopece P.,CIVEN | Moretto L.M.,University of Venice | Ugo P.,University of Venice
Lecture Notes in Electrical Engineering | Year: 2014

The results of a study on the determination of trace levels of arsenic with nano-electrode ensembles (NEEs) are reported. The method is characterized by detection limit as low as 5 ng/L (65 pM) after 3 min preconcentration at -0.4 V. NEEs were applied to trace As analysis in real samples such as certified seawater samples. © 2014 Springer Science+Business Media.


Enrichi F.,CIVEN | Ricco R.,CIVEN | Scopece P.,CIVEN | Parma A.,CIVEN | And 4 more authors.
Journal of Nanoparticle Research | Year: 2010

In this study, we report the comparison between Eu3+-doped silica nanoparticles synthesized by Stöber method using Eu(NO 3)3 or Eu(acac)3 as precursors. The impact of different europium species on the properties of the final silica nanospheres is investigated in details in terms of size, morphology, reachable doping amount, and luminescence efficiency. Moreover, the results obtained for different thermal treatments are presented and discussed. It is shown that the organic complex modify the silica growing process, leading to bigger and irregular nanoparticles (500-800 nm) with respect to the perfectly spherical ones (400 nm) obtained by the nitrate salt, but their luminescence intensity and lifetime is significantly higher when 800-900 °C annealing is performed.


Ricco R.,CIVEN | Meneghello A.,CIVEN | Enrichi F.,CIVEN
Biosensors and Bioelectronics | Year: 2011

DNA microarray is a powerful tool for the parallel of nucleic acids and other biologically significant molecules. In this communication we report an easy and cheap synthesis route for incorporating organic dyes into monodisperse inorganic silica nanoparticles and their application on the detection of carcinogenic risky Human Papilloma Virus using DNA microarray technology. We correlate our system with conventional direct dyes and commercial quantum dots, with a promising increase in optical signal, and a related decrease of the limit of detection, thus giving a remarkable improvement in this technique towards early diagnosis of diseases and trace level detection of dangerous biological contaminants. © 2010 Elsevier B.V.


Alonso U.,CIEMAT | Missana T.,CIEMAT | Patelli A.,CIVEN | Ceccato D.,University of Padua | And 2 more authors.
Applied Geochemistry | Year: 2014

Risk assessment of deep geological repositories (DGR) for high level radioactive waste demands radionuclide (RN) sorption data, with minimised uncertainties, on repository barriers. Sorption data in crystalline rocks, are principally obtained on crushed material and reported as distribution coefficients, relative to the mass of solid (Kd in m3/kg). Main sources of uncertainty on available sorption data are due to differences in experimental approach (comparison of crushed and intact material), groundwater and rock composition, redox conditions or the high heterogeneity of crystalline rock.In this study, the effect of rock mineral heterogeneity on selenium(IV) surface distribution on diorite crystalline rock was analysed under oxic and anoxic conditions. The micro-Particle Induced X-ray Emission (μPIXE) ion beam technique was selected because it allows quantifying tracer distribution directly on intact rock samples, at mineral micro-scale.Diorite samples were extracted from the Äspö underground research laboratory (Sweden), handled and transported under anoxic conditions. Maintaining controlled redox conditions during the whole experiment is considered particularly relevant to preserve real repository conditions.Selenite distribution on Äspö diorite surface was heterogeneous, its retention being higher under anoxic conditions. By μPIXE analyses the main Se retentive regions were identified, equivalent in both oxic/anoxic conditions, and surface distribution coefficients (Ka) were determined on main diorite minerals. Sorption values ranged from near zero, on quartz or K-feldspars, to higher values on Fe-bearing minerals like biotite (Ka~7×10-5m) under anoxic conditions. Experimental Ka values determined here are compared to reported distribution coefficients (Kd). © 2014 Elsevier Ltd.


PubMed | CIVEN
Type: Journal Article | Journal: Biosensors & bioelectronics | Year: 2011

DNA microarray is a powerful tool for the parallel of nucleic acids and other biologically significant molecules. In this communication we report an easy and cheap synthesis route for incorporating organic dyes into monodisperse inorganic silica nanoparticles and their application on the detection of carcinogenic risky Human Papilloma Virus using DNA microarray technology. We correlate our system with conventional direct dyes and commercial quantum dots, with a promising increase in optical signal, and a related decrease of the limit of detection, thus giving a remarkable improvement in this technique towards early diagnosis of diseases and trace level detection of dangerous biological contaminants.

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