762 research outputs found
Global Attractivity for Reaction-Diffusion Systems. The Case of Nondiagonal Diffusion Matrices
No full textAbstractThis paper treats the global attractivity of uniform steady solutions of reaction-diffusion systems subject to suitable Neumann, Dirichlet, or third type (Robin) boundary conditions. Particular emphasis to the case of nondiagonal matrices of diffusion coefficients is given. Applications to classical problems in ecology and relevant problems in epidemic theory are analyzed
Asymptotic behaviour of reaction-diffusion systems in population and epidemic models. The role of cross diffusion.
No full textControlled growth of carbon nanotubes for electronic and photovoltaic applications
No full textCarbon nanotubes (CNTs), experimentally observed for the first time twenty years ago, have triggered an unprecedented research effort, on the account of their astonishing structural, mechanical and electronic properties. Unfortunately, the current inability in predicting the CNTs’ properties and the difficulty in controlling their position on a substrate are often limiting factors for the application of this material in actual devices. This research aims at the creation of specific methodologies for controlled synthesis of CNTs, leading to effectively employ them in various fields of electronics, e.g. photovoltaics. Focused Ion Beam (FIB) patterning of Si surfaces is here proposed as a means for ordering the assembly of vertical-aligned CNTs. With this technique, substrates with specific nano-structured morphologies have been prepared, enabling a high degree of control over CNTs’ position and size. On these nano-structured substrates, the growth of CNTs has been realized by chemical vapor deposition (CVD), i.e. thermal decomposition of hydrocarbon gases over a heated catalyst. The most common materials used as catalysts in CVD are transition metals like Fe and Ni; however, their presence in the CNT products often results in shortcomings for electronic applications, especially for those based on silicon, being the metallic impurities incompatible with very-large-scale integration (VLSI) technology. In the present work the role of Ge dots as an alternative catalysts for CNTs synthesis on Si substrates has been thoroughly assessed, finding a close connection between the catalytic activity of such material and the CVD conditions, which can affect both size and morphology of the dots. Successful CNT growths from Ge dots have been obtained by CVD at temperatures ranging from 750 to 1000°C, with mixtures of acetylene and hydrogen in an argon carrier gas. The morphology of the Si surface is observed to play a crucial role for the outcome of the CNT synthesis: natural (i.e. chemical etching) and artificial (i.e. FIB patterning, nanoindentation) means of altering this morphology in a controlled way have been then explored to optimize the CNTs yield. All the knowledge acquired in this study has been finally applied to synthesize CNTs on transparent conductive electrodes (indium-tin oxide, ITO, coated glasses), for the creation of a new class of anodes for organic photovoltaics. An accurate procedure has been established which guarantees a controlled inclusion of CNTs on ITO films, preserving their optical and electrical properties. By using this set of conditions, a CNTenhanced electrode has been built, contributing to improve the power conversion efficiency of polymeric solar cells
sj-docx-1-eso-10.1177_23969873221100897 – Supplemental material for Endovascular treatment in patients with acute ischemic stroke and cancer: Systematic review and meta-analysis
No full textSupplemental material, sj-docx-1-eso-10.1177_23969873221100897 for Endovascular treatment in patients with acute ischemic stroke and cancer: Systematic review and meta-analysis by Danilo Caimano, Federica Letteri, Francesco Capasso, Nicola Limbucci, Patrizia Nencini, Cristina Sarti, Fana Alemseged, Guido Bigliardi, Andrea Morotti, Danilo Toni, Andrea Zini and Francesco Arba in European Stroke Journal</p
Interface of graphane with copper : a van der Waals density-functional study
No full textVarious forms of hydrogenated graphene have been produced to date by several groups, while the synthesis of pure graphane has not been achieved yet. The study of the interface between graphane, in all its possible hydrogenation configurations, and catalyst metal surfaces can be pivotal to assess the feasibility of direct CVD growth methods for this material. We investigated the adhesion of graphane to a Cu(111) surface by adopting the vdW-DF2-C09 exchange-correlation functional, which is able to describe dispersion forces. The results are further compared with the PBE and the LDA exchange-correlation functionals. We calculated the most stable geometrical configurations of the slab/graphane interface and evaluated how graphane's geometrical parameters are modified. We show that dispersion forces play an important role in the slab/graphane adhesion. Band structure calculations demonstrated that in the presence of the interaction with copper, the band gap of graphane is not only preserved, but also enlarged, and this increase can be attributed to the electronic charge accumulated at the interface. We calculated a substantial energy barrier at the interface, suggesting that CVD graphane films might act as reliable and stable insulating thin coatings, or also be used to form compound layers in conjunction with metals and semiconductors
Zibaldoni e repertori da Bartolommeo Capasso a Luigi Volpicella
No full textL’autore ricostruisce il metodo di lavoro di due storici, Bartolommeo Capasso (1815-1900), uno dei fondatori della Società Napoletana di Storia patria, e Luigi Volpicella iunior (1864-1949), attraverso le loro carte, custodite dalla Società, contenenti appunti e spogli delle fonti primarie e della bibliografia. Verrà evidenziato il legame tra il modo con cui Capasso classificava le informazioni e il metodo umanistico dei notabilia. Per Volpicella ci si soffermerà sulle carte geografiche che predispose come atti preparatori dei profili biografici da lui pubblicati a corredo di un’edizione documentaria.
The author reconstructs the working method of two historians, Bartolommeo Capasso (1815-1900), one of the founders of the Società Napoletana di Storia patria, and Luigi Volpicella junior (1864-1949), through their papers preserved by the Società. These documents contain notes and extracts from primary sources and bibliography. The connection between Capasso’s information management and the humanistic method of notabilia is highlighted. As for Volpicella, emphasis is placed on the geographical maps he produced as preparatory acts for the biographical profiles he published in a documentary edition
Innovation in industrial districts: evidence from Italy
No full textPurpose - The recent transformations brought about by the globalisation of markets have increased the competitive pressure for firms operating in traditional sectors, and in particular for those in industrial districts. The authors' aim is to understand the extent to which firms responded to these new challenges. More particularly, they investigate the determinants of innovation at firm level focusing on the role of firm's outsourcing strategies. Design/methodology/approach - Drawing on an original firm-level dataset, the authors analyse the determinants of innovation in a typical Italian industrial district, i.e. the hosiery district of Castel Goffredo in the Third Italy. They apply econometric techniques, in particular OLS and Tobit models. Findings - The authors' findings suggest that industrial districts are evolving towards a differentiated organisational structure in which innovation is driven by firms, which are focused on core competences and high valued added activities. Research limitations/implications - The authors' results should be interpreted with some caution, since the cross-sectional design of their data does not allow them to fully control for potential reverse causation effects, which might be relevant for some of the explanatory variables. Their data do not allow them to include additional instrumental variables, thus they cannot control for endogeneity. Therefore, their interpretation is limited to comment the extent and regularity of the relation between dependent and explanatory variables. Practical implications - The evidence presented in this study corroborates some arguments highlighted in the current debate about the evolution of industrial districts. A network-based organisation is the dominant organisational structure. The authors have some evidence on the importance of size as driver of innovation. Originality/value - The authors find original evidence at firm level on the relation between organisational change, in the form of outsourcing, and innovation in the context of an industrial district. They also find empirical support to arguments debated in the recent policy debates on whether small firms can be regarded as engines of innovation in industrial districts
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