Investigation into the interactions between filler and elastomers used for tyre production

An investigation in the interactions between silica and elastomers used in the production of tyre treads was carried out. To achieve some knowledge on the interactions between reinforcing agent and elastomers, which are fundamental in determining the rubber reinforcement, inverse gas chromatography (IGC) at infinite dilution was used to evaluate surface properties of both unmodified and modified silica and to calculate the adsorption free energy and enthalpy of low molecular weight analogues of elastomers. The predictions derived from the thermodynamic study were compared with some of the results obtained by a morphological analysis of silica-filled compounds carried out by transmission electron microscopy (TEM) and automated image analysis (AIA).     

Study of the laser cleaning on plaster sculptures. The effect of laser irradiation on the surfaces

The focus of this paper is to study the effects caused by the laser irradiation on nineteenth and twentieth century plaster sculptures. Before applying the laser cleaning on the sculptures, it was tested on samples prepared in laboratory according to the results of the scientific investigation carried out on the selected works of art. The characterization of the surface finishing materials of the sculptures was performed by Fourier Transform Infrared spectrometry (FTIR), X-ray Fluorescence spectroscopy (XRF), UV fluorescence photography, and internal micro stratigraphic analysis. Regarding the finishing materials, shellac, zinc white, siccative oil and proteins were found on the surfaces. The results of the scientific investigation, together with the examination of the ancient technical manuals, were used to create the laboratory samples to carry out the irradiation tests with laser. The laser irradiation and cleaning tests were carried out with a Q-switched Nd:YAG system. The irradiated surfaces were analyzed before and after the laser tests with the aid of a video microscope and a reflectance spectrophotometer, in order to evaluate the color changes of the surfaces. The possible morphological modifications caused by laser irradiation were also investigated by Scanning Electron Microscopy (SEM) together with ancillary Energy Dispersive Spectroscopy (EDS) elemental analysis. Concerning the laser cleaning test on the samples, in general little color changes were observed both with the 532 and 1064 nm wavelength. Total color changes, expressed as ΔE*, are always small apart from the samples made of shellac and zinc white in linseed oil, as finishing layer. As regards these samples the surface irradiated with the laser greyed lightly, corresponding to a decrease of L* parameter (lightness). SEM imaging of the treated and not-treated samples, both at low and high magnification, does not show evidence of significant morphological differences due to the laser beam irradiation. Starting from these results, some laser cleaning tests were carried out on the original sculptures, putting them in comparison with an aqueous cleaning method. It was found that the laser cleaning removes effectively the dirt layer preserving the original finishing on the sculpures’ surface, whereas the aqueous cleaning system removes also the finishing.     

On Separation of Variables for Homogeneous SL(r) Gaudin Systems

By means of a recently introduced bihamiltonian structure for the homogeneous Gaudin models, we find a new set of Separation Coordinates for the sl(r) case.      

Cobalt Growth on the Tips of CdSe Nanorods

Best of both worlds : Reduction of an organometallic Co precursor on preformed CdSe nanorods yields two distinct semiconducting–magnetic heterostructures (see picture). The selective growth of Co on the tips of CdSe first gives nanosphere–nanorod dimers, which evolve into nanorod–nanorod structures. In the hybrid objects the magnetic properties of Co remain intact, while the luminescence properties of CdSe are affected but not completely quenched.

     

Near equiatomic FeCo nanocrystalline alloy embedded in an alumina aerogel matrix: microstructural features and related magnetic properties

FeCo-Al2O3 nanocomposite aerogels were studied by high-resolution electron microscopy, energy filtered transmission electron microscopy, M?ssbauer spectroscopy, and measurements of static magnetizations and hysteretic behavior. The combined use of such techniques provided insights on the formation of bcc FeCo nanocrystalline particles inside the alumina matrix, which is promoted by thermal treatment under hydrogen flow of the parent aerogel. Sample characteristics such as alloy composition and crystallinity, influence of the matrix on the structural evolution, and resulting magnetic properties were investigated as a function of the temperature and time of the reduction treatment.     

A note on the global structure of supermoduli spaces

We recall some deformation theory of Susy-curves and study obstructions to projectedness of supermoduli spaces, both from a general standpoint and by means of the local coordinate charts most commonly used in the physical literature. We prove that these give rise to a projected atlas for genusg=2 only.Work partially supported by the National Project Geometria e Fisica, M.P.I.     

The influence of composition and porosity on the magnetic properties of FeCo-SiO2 nanocomposite aerogels

FeCo-SiO2 aerogel nanocomposites with different porosity were obtained using two different sol-gel procedures: the first involves a single acidic step and gives rise to relatively dense aerogels while the second procedure allows one to obtain highly porous aerogels using urea in the second step to promote fast gelation. Samples with different loading of FeCo equimolar alloy and with different Fe : Co ratios were prepared. The magnetic properties of all the nanocomposite aerogels were extensively studied as a function of porosity and composition. Particular attention was paid to the role played by the interparticle interactions, which are mediated by the silica matrix, in determining the collective magnetic behaviour. The kind and strength of magnetic interactions are affected by both the composition and the porosity of the matrix.     

One-pot synthesis and characterization of size-controlled bimagnetic FePt-iron oxide heterodimer nanocrystals

A one-pot, two-step colloidal strategy to prepare bimagnetic hybrid nanocrystals (HNCs), comprising size-tuned fcc FePt and inverse spinel cubic iron oxide domains epitaxially arranged in a heterodimer configuration, is described. The HNCs have been synthesized in a unique surfactant environment by temperature-driven sequential reactions, involving the homogeneous nucleation of FePt seeds and the subsequent heterogeneous growth of iron oxide. This self-regulated mechanism offers high versatility in the control of the geometric features of the resulting heterostructures, circumventing the use of more elaborate seeded growth techniques. It has been found that, as a consequence of the exchange coupling between the two materials, the HNCs exhibit tunable single-phase-like magnetic behavior, distinct from that of their individual components. In addition, the potential of the heterodimers as effective contrast agents for magnetic resonance imaging techniques has been examined.