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Marina di Pisa, Italy

Antonetti C.,University of Pisa | Toniolo L.,University of Venice | Cavinato G.,University of Padua | Forte C.,CNR Institute of Chemistry of organometallic Compounds | And 4 more authors.
Applied Catalysis A: General | Year: 2015

An organic-inorganic hybrid material, PK-SiO2 (PK = polyketone), was employed as support for Pd catalysts. Their synthesis was carried out by MW irradiation of an ethanol solution of Pd(OAc)2 in the presence of the support. The obtained systems were characterized by solid state NMR, SEM, TEM, ICP, XPS, BET, gas porosimetry and tested in two probe reactions: the selective hydrogenation of cinnamaldehyde to hydrocinnamaldehyde carried out in decalin and the oxidation of 1-phenylethanol to acetophenone in water. For comparison, Pd/PK and Pd/SiO2 catalysts were also prepared by using the same procedure, characterized and tested in the same reactions. On the hybrid support the Pd nanoparticles resulted significantly smaller and with a more homogeneous size distribution compared to those on bare SiO2 or PK. The catalysts on the hybrid support allowed a higher performance and could be recycled up to five times without loss of activity and metal leaching. These results were related to the improved surface area of the hybrid material (compared to the low surface area of bare PK) ascribable to silica introduction, combined with the stabilizing effect of the polymeric counterpart against Pd nanoparticles agglomeration. © 2015 Elsevier B.V. All rights reserved.

Tallawi M.,Friedrich - Alexander - University, Erlangen - Nuremberg | Dippold D.,Friedrich - Alexander - University, Erlangen - Nuremberg | Rai R.,Friedrich - Alexander - University, Erlangen - Nuremberg | D'Atri D.,Largo Lucio Lazzarino | And 5 more authors.
Materials Science and Engineering C | Year: 2016

Nano- and micro-scale topographical features play a critical role in the induction and maintenance of various cellular properties and functions, including morphology, adhesion, gene regulation, and cell-to-cell communication. In addition, recent studies have indicated that the structure and function of heart tissue are also sensitive to mechanical cues at the nano- and micro-scale. Although fabrication methods exist for generating topographical features on polymeric scaffolds for cell culture, current techniques, especially those with nano-scale resolution, are typically complex, prohibitively expensive and not accessible to most biology laboratories. Here, we present a simple and tunable fabrication method for the production of patterned electrospun fibers that simulate the complex anisotropic and multi-scale architecture of cardiac tissue, to promote cardiac cell alignment. This method is based on the combination of electrospinning and soft lithography techniques, in which electrospun fibers, based on a blend of poly(glycerol sebacate) and poly(caprolactone), were collected on a patterned Teflon-coated silicon wafer with imprinted topographical features. Different surface topographies were investigated, such as squares and grooves, with constant or different interspatial distances. In vitro cell culture studies successfully demonstrated the alignment of both C2C12 myoblasts and neonatal rat cardiomyocytes on fabricated electrospun patterned surfaces. C2C12 cells were cultured over a period of 72 h to study the effect of topographical cues on cell morphology. Cells attached within the first 8 h after seeding and after 24 h most of the cells started to align responding to the topographical cues. Similarly, cardiomyocytes responded to the topographical features by aligning themselves and by expressing Connexin 43 along cellular junctions. Summarizing, we have developed a new method with the potential to significantly promote cardiac tissue engineering by fabricating electrospun fibers with defined topographical features to guide and instruct donor and/or host cells. © 2016 Elsevier B.V.

D'Andrea E.,Largo Lucio Lazzarino | Pagnotta S.,CNR Institute of Chemistry of organometallic Compounds | Grifoni E.,CNR Institute of Chemistry of organometallic Compounds | Lorenzetti G.,CNR Institute of Chemistry of organometallic Compounds | And 3 more authors.
Spectrochimica Acta - Part B Atomic Spectroscopy | Year: 2014

The usual approach to laser-induced breakdown spectroscopy (LIBS) quantitative analysis is based on the use of calibration curves, suitably built using appropriate reference standards. More recently, statistical methods relying on the principles of artificial neural networks (ANN) are increasingly used. However, ANN analysis is often used as a 'black box' system and the peculiarities of the LIBS spectra are not exploited fully. An a priori exploration of the raw data contained in the LIBS spectra, carried out by a neural network to learn what are the significant areas of the spectrum to be used for a subsequent neural network delegated to the calibration, is able to throw light upon important information initially unknown, although already contained within the spectrum. This communication will demonstrate that an approach based on neural networks specially taylored for dealing with LIBS spectra would provide a viable, fast and robust method for LIBS quantitative analysis. This would allow the use of a relatively limited number of reference samples for the training of the network, with respect to the current approaches, and provide a fully automatizable approach for the analysis of a large number of samples. © 2014 Elsevier B.V.

Frendo F.,Largo Lucio Lazzarino | Bertini L.,Largo Lucio Lazzarino
International Journal of Fatigue | Year: 2015

The fatigue resistance of a pipe-to-plate welded joint was investigated under combined in-phase and out-of-phase (changing principal directions) bending and torsion. The specimen consisted of a pipe having 64 mm outer diameter and 10 mm thickness, which is joined by fillet welding to a 25 mm thickness plate. The pipe and plate were made of S355 steel and the joint was not subjected to any after welding relieve treatment. This work represent an extension of a previous work by the authors, in which the fatigue resistance of the same joint was investigated under bending, torsion and combined in-phase loading. A new experimental arrangement, making use of two independent hydraulic actuators, was developed to have the possibility of making out of phase tests. Four series of tests were then carried out in the life range 105-2·106, with two bending to torsion ratios (i.e. σ/τ=3.25 and σ/τ=0.88) and two load ratios (i.e. R=-1 and R=0). For the examined joint, failures originated from the weld root, where a severe notch is present. The results confirmed a lower fatigue endurance in case of out-of-phase loading, by a factor ranging from 2 to 8 depending on the number of cycles and on the adopted failure hypothesis. © 2015 Elsevier Ltd. All rights reserved.

Bertini L.,Largo Lucio Lazzarino | Cera A.,Trenitalia S.p.A. Direzione Tecnica | Frendo F.,Largo Lucio Lazzarino
International Journal of Fatigue | Year: 2014

The fatigue resistance of pipe to plate fillet welding connections was experimentally investigated. The specimens consisted of steel tubular elements, having 10 mm wall thickness and 64 mm external diameter, joined by seam welding to a plate of 25 mm thickness and were designed in order to reproduce a typical joint used in railway bogie frames. Tests were carried out under pure bending, pure torsion and under combined in-phase loading, with two different bending-to-torsion ratios. For each loading condition, tests were conducted with R=0 (i.e. pulsating fatigue) and R=-1 (i.e. alternating fatigue). The results, obtained on the basis of the nominal stress method, show an almost independent behaviour on the load ratio R for the torsion loading and a significant effect of the load ratio R in case of bending loading. A modified equivalent stress, based on the results obtained under pure bending/torsion, is demonstrated to fit all the experimental results with a reduced scatter and a higher slope, with respect to the frequently used von Mises equivalent stress. © 2014 Elsevier Ltd. All rights reserved.

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