Magnetic properties and phase stability in Co-Ni base alloy thin films

Co-Ni base thin films were deposited by reactive radio frequency magnetron sputtering in N₂+Ar atmosphere at different partial pressure ratios. Only the nitrogen content in the films changes when changing . Amorphous magnetic films can be obtained for compositions around N/Co=1–1.5, whereas higher N₂ contents lead to non-magnetic nitride phases. Significant changes in structural and magnetic properties are observed upon heating thin films in a TG(M) apparatus. Only the sample having a N/Co=1.5, when heat treated, appears to be made of a stable ferromagnetic phase. The N content is appropriate to keep Cr, Al and N, which exert an adverse effect on the magnetization of Co-Ni base alloys, out of the ferromagnetic phase in the form of separated nitride phases. PACS 68.55.-a; 68.60.Dv; 68.18.Jk; 75.70.Ak; 75.75.+a; 85.70.-w     

Characterization of electrochemically synthesized alkylpyrrole intrinsically conducting polymers

This work concerns some electrochemical polymerizations of pyrrole derivatives in order to obtain intrinsically conducting polymers: the study was mainly concerned with the electrochemical polymerization of 3‐alkyl substituted pyrroles with different chain lengths (3‐hexylpyrrole, 3‐decylpyrrole, 3‐hexadecylpyrrole). Different experimental conditions were adopted with 3‐alkylpyrroles: different solvents (propylene carbonate, acetonitrile), different counterions (ClO₄⁻, BF₄⁻, NO₃⁻, PF₆⁻, TsO⁻) and different current densities (0.05, 0.1, 0.2, 0.4 mA/cm²). The synthesized conducting polymers were characterized through Fourier transform infrared spectroscopy, ¹³C cross‐polarization magic angle spinning solid‐state nuclear magnetic resonance and electrical conductivity measurements to study the relations connecting the experimental conditions of synthesis with the structure and electrical properties of the polymers. Thermogravimetric analysis, differential scanning calorimetry and isothermal heatings were performed in order to evaluate the polymer's thermal stability. Copyright © 2000 John Wiley & Sons, Ltd.     

Analytical Techniques Applied to the Study of Industrial Archaeology Heritage: The Case of Plaiko Zubixe Footbridge

In this work, micro-Raman spectroscopy and micro-energy-dispersive X-ray fluorescence spectroscopy (µ-EDXRF) were applied on microsamples taken from the Plaiko Zubixe footbridge (1927) located in Ondarroa (Basque Country, Spain) in order to investigate the original paint coating and make an evaluation of the conservation state before its restoration. Elemental and molecular images were acquired for the study of the compounds distribution. Some modern pigments such as phthalocyanine blue and green pigments, minium, calcium carbonate, Prussian blue, and hematite were identified. Barium sulfate and titanium dioxide were recognized as opacifier agents. Thanks to the study of the stratigraphies, it has been possible to determine the original paint layer, which includes lead white, ultramarine blue, carbon black, and barium sulfate. In addition, colorimetric analyses made it possible to know the CIELab values of the original layer in order to reproduce the original colour during the planned restoration work. The massive presence of chlorine detected by µ-EDXRF and the corrosion products of the rust layer, in particular akaganeite and hematite, highlighted the atmospheric impact in the conservation of the bridge because they were due to the effect of both marine aerosol and to the presence of acidic components in the environment coming from anthropogenic activity. This work demonstrated the usefulness of a scientific approach for the study of industrial archaeology heritage with the aim to contribute to its conservation and restoration.     

A splitting property of the upper bounded-Hausdorff convergence

We provide a characterization, based on a splitting property, for the upper bounded-Hausdorff convergence of a net of closed sets. Furthermore, we use this property to describe the local structure of the upper bounded-Hausdorff topology.The author is indebted to S. Levi and R. Lucchetti for continuous suggestions and encouragements.     

Interaction enthalpy of lysozyme with vesicles

Negatively charged vesicles made of non-stoichiometric amounts of sodium dodecylsulfate and cetyltrimethylammonium bromide were characterised by physico-chemical methods. Interactions with lysozyme were examined by calorimetry. A remarkable heat effect is observed upon diluting the protein with the vesicular pseudo-solvent. The maximum ΔH_bind value occurs at complete vesicle charge neutralisation by the protein.     

Spectroscopic method for the analysis of polyalkenamers

A method based on use of NMR and infrared spectroscopy is described for the quantitative determination of the structural units generally occurring in polyalkenamers. The possibilities offered by both techniques are pointed out: in particular, the values found for the absorptivities of the infrared bands typical of unsaturated alkenamer units are extensively discussed.     

A wavelength-selective directional coupler based on a boundary-condition-modulation grating: proposal,theory, and preliminary results

A nonconventional wavelength-selective grating-assisted vertical coupler is proposed and analysed. Its novelty consists in the grating position: neither between nor above the waveguide cores, but in a lateral region. Analytic and numerical results indicate that, for devices that are not yet optimized, frequency selectivity and/or device length are at least comparable with those of conventional grating-assisted filter-couplers. Potential advantages of the new device, in terms of performance and of manufacturing technology, are discussed.     

On the geometrical structure of Euler-Lagrange equations

Summary We show that the Euler-Lagrange operator and the Poincaré-Cartan form arise in a very simple and natural way from the contact structure of the second order jet space, in a purely differential context, without any reference to a variational problem. By the way we obtain an intrinsic expression of the Euler-Lagrange operator.