The role of precursor gases on the surface restructuring of catalyst films during carbon nanotube growth

Catalyst films undergo considerable surface morphology restructuring prior to carbon nanotube nucleation, deeply influencing the nanostructures obtained. Here we study the influence of different gaseous atmospheres on the structure of thin Fe films. The morphology is influenced by process temperature and substrate interactions and varying the gas type and pressure can control the average catalyst island height.     

Substrates for flexible electronics: A practical investigation on the electrical,film flexibility,optical, temperature,and solvent resistance properties

Designing and developing flexible electronics requires a thorough investigation of the substrates available for the fabrication of devices. Here, we present a practical study on a variety of significant substrates: polyethylene terephthalate (PET), its heat‐stabilized (HS) derivative, HS‐PET, and polyethylene naphthalate (PEN) plastic insulating films; indium tin oxide (ITO)‐coated ITO/PEN and ITO/PET transparent conducting films; rigid ITO/glass and FTO/glass substrates; stainless steel and titanium foils. We put the substrates through a range of tests these actually undergo during device fabrication to determine their optical, mechanical flexibility (under different types of tensile and compressive stress bending with and without a PEDOT:PSS conducting polymer layer), solvent resistance, stability to temperature treatment (conductivity and deformation), and to UV irradiation. We highlight issues and propose solutions to improve substrate response. The results and thresholds extracted reveal limitations and windows of opportunity useful for the designer of flexible optoelectronics in determining manufacturing processes and the final applications under everyday operation. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011     

Near-Curie magnetic anomaly at the Ni/C interface observed by electron holography

We analyze with electron holography carried out in a transmission electron microscope the near-Curie behavior of magnetism at the edge of a Nickel thin film coated with Carbon. In-situ experiments with finely controlled variations of the sample temperature reveal an anomaly in the ferromagnetic to paramagnetic phase transition when the film temperature is a few degrees above the nominal Curie point. We interpret the anomaly as a strain-induced spin reorientation transition triggered by the differential thermal expansion of Carbon and Nickel. We present a model that quantitatively reproduces the main features of the observed signal. The model is developed in terms of an anisotropic, temperature dependent exchange coupling between the Nickel moments at the Carbon interface that favors their vertical alignment at low temperatures.     

GNO and its performances

GNO (Gallium Neutrino Observatory) is monitoring the low energy solar neutrino flux at Laboratori Nazionali del Gran Sasso. I describe the main features of the experiment, the goals, and the recent results.     

Characterisation of young Cognac spirit aromatic quality

In order to determine the quality of young Cognac spirits, mainly appreciated by the absence of defects, a new method has been developed, based on sniffing and olfactometry (GC-O) and associated with sensory and chemical analysis. During 3 years, good quality spirits selected first by Cognac merchant were analysed and selected by an original panel of tasters used to judge those spirits. The aromatic profile were established and compared. Then, the most different spirits were analysed by sniffing coupled with gas chromatography. The olfactometric profile obtained were compared. We noticed that they have all the same aromatic base constituted with 18 specific areas. Six of them were unknown and we are trying now to identify them.     

Calculation of second topological moment of two entangled polymers

We set up a field theoretical model based on Abelian Chern-Simons field theories to describe the topological entanglement of two polymers. The topological states of the system are distinguished using the link invariant of Gauss. The second topological moment of the two polymers , where m is the linking number, is exactly computed by field theoretical methods. The result is applied to estimate approximatively the mean square average of the linking number of a polymer P₁ in a dilute solution with other polymers.     

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The Kaluza-Klein theory and four-dimensional spacetime

The conventional electromagnetism, which includes Maxwell's field equations and the Lorentz force relation, does not provide an explanation of well-known electromagnetic phenomena, such as the Aharonov-Bohm interference effect and the Meissner-Ochsenfeld effect in superconductors. In this paper, it is shown that the Kaluza-Klein five-dimensional theory suggests a simple explanation of these effects on a unified basis.