53 research outputs found
Due cuori e una baracca
No full textLe vite da burattinai di Giuseppina Cazzaniga e Benedetto Ravasio vengono raccontate, tra aneddotica e cronaca, nei saggi di Lorenzo Pezzica e Francesca Cecconi.I due coniugi hanno attraversato il panorama complesso dell’Italia del Novecento ponendo al centro della loro scelta di vita la ricerca artistica. Si sono confrontati e scontrati con le trasformazioni sociali che hanno guidato l’evoluzione del Teatro di Figura, lasciandoci in eredità un patrimonio che dalla tradizione ci proietta nel futuro.Il libro è arricchito da immagini inedite dall'Archivio storico della Fondazione Ravasio di Bergamo
Natural surface-film studies in shallow coastal waters of the Baltic and Mediterranean seas.
No full textAuthor to whom correspondence should be addressed at: Environmental Acoustics Laboratory, University of Gdansk, Wita Stwosza 57, 80–952 Gdansk, Poland
Quantitative Study of Porosity and Pore Features in Moldavites by Means of X-ray Micro-CT
Get PDFX-ray micro-computer aided tomography (μ-CT), together with optical
microscopy and imaging, have been applied to the study of six moldavite samples. These
techniques enabled a complete characterization to be made of the textural features of both
Muong Nong-type and common splashform moldavites. A detailed study of the size and
distribution of pores or bubbles confirmed the marked variability in pore size among the
samples, as well as within each sample, and indicated in the Muong Nong-type moldavites the
presence of at least two deformation stages which occurred before and after pore formation
Cobalt monolayer islands on Ag (111) for ORR catalysis
No full textThe design of a catalyst for one of the most important electrocatalytic reactions, the oxygen reduction reaction (ORR), was done following the most recent guidelines of theoretical studies on this topic. Aim of this work was to achieve a synergic effect of two different metals acting on different steps of the ORR. The catalytic activity of Ag, already known and characterized, was enhanced by the presence of a monolayer of cobalt subdivided into nanosized islands. To obtain such a controlled nanostructure, a novel method utilizing self-assembled monolayers (SAMs) as templates was employed. In a recent study, we were able to perform a confined electrodeposition of cobalt onto Ag(111) in a template formed by selectively desorbing a short-chain thiol (3-mercaptopropionic acid, MPA) from binary SAMs using 1-dodecanthiols (DDT). [32] This method allows for an excellent control of the morphology of the deposit by varying the molar ratio of the two thiols. Because cobalt does not deposit on silver at an underpotential, the alternative approach of surface limited redox replacement (SLRR) was used. This method, recently developed by Adžić et al.,13 consists of the use of a monolayer of a third metal, which can be deposited at an underpotential, as a template for the spontaneous deposition of a more noble metal. Herein, we choose zinc as template for the deposition of cobalt. Ag(111) crystals were covered by monolayer islands consisting of cobalt, with the surface atomic ratios ranging from 12 to 39 % for cobalt. The catalytic activity of such samples towards ORR was evaluated and the best improvement in activity was found to be that of the sample with a cobalt percentage of approximately 30 % with respect to the bare silver, which is in good agreement with theoretical hypotheses
Interfacial Properties of Nanoparticle-Surfactant Systems
No full textThe utilisation of solid micro/nanoparticles particles in association with surfactants represents an attractive route to control drop/bubble coalescence or liquid film stability in foam and emulsion technology. In fact, the transfer/attachment of nanoparticles to liquid interfaces, driven by their partial wettability, strongly modifies the mechanical properties of the interfacial layers. At large surface coverage, particles can build solid-like barriers to coalescence, such as particle networks, while at low surface coverage, small particles segregating at the interface may play a role more similar to surfactants, affecting equilibrium and dynamic interfacial tension. Surfactant adsorption at the particle surface can be utilised to control such situations, by tuning the hydrophilic/hydrophobic character of the particles and then their ability to form interfacial layers. For these mixed particle-surfactant systems interfacial properties, such as dynamic interfacial tension are still poorly investigated. These studies, however, can bring important information on the undergoing dynamic processes associated with particles and surfactant transfer and organisation at the interface and are essential to understand how to achieve film stabilisation by the smallest amount of particles or surfactant. Previous investigations [1.2] have shown the effectiveness of dilational rheology in providing a better comprehension of dynamic mechanisms occurring in the interfacial layer. In some cases, rheological studies allow in fact the equilibrium and kinetic parameters related to the structure of the particle layer and to the particle interaction to be accessed. Here, we summarise results obtained for interfacial layers containing silica or alumina nanoparticles, which can be utilized as stabilisers for foams and/or emulsions. Different degree of hydrophobicity and, consequently, different affinity with the water/oil interfaces is obtained by using specific anionic or cationic surfactants. The results for a particular arrangement with the surfactant soluble only in the oil phase and hydrophilic particles dispersed in the aqueous phase, where the surfactant-nanoparticle interaction occurs only at the interface, is also reported. [1]. F. Ravera, E. Santini, G. Loglio, M. Ferrari, L. Liggieri, J. of Physical Chemistry B, /10,, 19543. 2006. [2]. F. Ravera, M. Ferrari, L. Liggieri , G. Loglio, E. Santini, A. Zanobini, Colloids Surf A. 323,, 99-108, 2006 1
Cadmium selenide electrodeposited by ECALE: electrochemical characterization and preliminary results by EXAFS.
No full text
In-Situ X-Ray analysis under controlled potential conditions: an innovative setup and its application to the investigation of ultrathin films electrodeposited on Ag(111)
No full textElectrochemical Atomic Layer Deposition of CdS on Ag Single Crystals: Effects of Substrate Orientation on Film Structure
No full textEffect of Silica Nanoparticles on Liquid-Liquid and Liquid-Air Interfacial Properties
No full textThe effect of particles at fluid interfaces is a topic of increasing interest especially for the application in the field of emulsions and foams. Colloidal nanoparticles are in fact utilised, often in association with surfactants, as stabiliser of such dispersed systems in different industrial fields. Particle stabilised foams and emulsions are also common in natural products and processes. In order to understand better the basic mechanisms underlying this stabilising effect, it is necessary to pay attention to the behaviour of the interfacial layer in these systems and in particular to the dilations properties of composite interfaces, which have been so far poorly investigated. In this work an experimental study is presented based on the measurement of surface properties of liquid/liquid and liquid/air systems, in the presence of colloidal nanoparticle. To this aim two drop tensiometers based on the drop profile acquisition and on the pressure acquisition are used. The coupling of these two methods allows the measurement of the dynamic and equilibrium interfacial tension and of the dilational visco-elastic modulus in a range of frequency from 0.001 to 100 Hz. The systems studied were CTAB aqueous solution at water/air and water/hexane interface in presence and in absence of colloidal suspension of spherical monodisperse silica nanometric particles. The measurements refer to different surfactant and solid concentrations. The effect of nanoparticles on the investigated interfacial properties is then interpreted according to proper thermodynamic and kinetic models
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