Electron energy loss spectroscopy measurement of surface vibration dispersion on clean and oxygen-covered Ni(100)

Inelastic electron scattering has been carried out at 300 K on Ni(100) and at 150 K on p(2 × 2) and c(2 × 2) oxygen overlayers adsorbed on Ni(100). Impact energies ranged from 4 to 300 eV in order to measure the dispersion curves of surface vibrations throughout the two-dimensional Brillouin zone in the [110] direction. The Rayleigh mode has been observed in all cases. On O-coved surfaces a surface resonance and two vibrations of different polarizations associated with oxygen motion have been detected. The polarizations of the detected modes and the origin of the resonances, arising from the folding of the Brillouin zone due to the adsorbate, have been analysed with the help of symmetry considerations and the EELS selection rules. The O-coverage dependence of the Rayleigh mode frequency suggests a continuous outwards expansion of the first Ni plane starting from a contracted clean surface. The O-dispersion data are consistent with an O layer distant from the first Ni plane by ～ 0.9 Å in both investigated overlayers.     

Local asymptotic stability for dissipative wave systems

We study the question of asymptotic stability, as time tends to infinity, of solutions of dissipative wave systems, governed by time-dependent nonlinear damping forces and by strongly nonlinear potential energies. This problem had been considered earlier for potential energies which arise from restoring forces, whereas here we allow as well for the effect of amplifying forces. Global asymptotic stability can then no longer be expected, and should be replaced by local stability. The conclusions are related to and supplement earlier work of Payne and Sattinger [7], who treated the nondissipative case, and of Hale [1], who showed the existence of connected global attractors.     

Time—Dependent Spatial Price Equilibrium Problem: Existence and Stability Results for the Quantity Formulation Model

This paper concerns with the study of the time–dependent variational inequality associated to the spatial price equilibrium model related to the quantity formulation. In particular existence the -orems of the solution to the associated variational inequality and a stability analysis of the equilibrium pattern is reported.     

Polycondensed nitrogen heterocycles. Part 24. Pyrrolo[3,4-c]isoquinolinone by thermal rearrangement of a pyrrolylbenzotriazinone

Rearrangement under acidic conditions of the pyrrolylbenzotriazinone 7 afforded the pyrrolylbenzamides 10 and 11 . By thermal rearrangement instead, the first fully aromatic derivative of the pyrrolo[3,4-c]isoquinoline ring system 9 was obtained.     

A new reverse mode light shutter from silica-dispersed liquid crystals

Nanoparticle dispersions in liquid crystalline materials at low concentrations allow both investigating the formation of defects in liquid crystal (LC) and enhancing the light-scattering properties of LC optical devices. Reverse mode LC dispersions are LC devices, which look like transparent in their OFF state, when no electric field is applied, and opaque in their ON state. In this paper, a new reverse mode device, formed by a dispersion of a LC mixture in a silica nanoparticle crosslinked network, is presented. The morphology and the electro-optical properties of these silica nanoparticle/LC composites were investigated for two different LC mixtures with a negative dielectric anisotropy. The observed transmittances and relaxation times were found to depend strongly on the silica amount and chemical–physical properties of LC used in the sample preparation.     

PCB-126 effects on aryl hydrocarbon receptor,ubiquitin and p53 expression levels in a fish product (Sparus aurata L.)

The aim of the present study is to determine if Ahr ligands as PCB-126, a dioxin-like, might contribute to inhibition of the tumour suppressor p53 by promoting its degradation through proteasome-ubiquitin system (UPS). The findings show, in the presence of PCB-126, a significant increase in p53 immunoreactivity in fish compared to the control. Subsequently, there is a decrease in p53 immunoreactivity at 24 h which is maintained even at 72 h. There is also a slight decrease in ubiquitin immunoreactivity to 12 h compared to the control and a marked decrease to 24 and 72 h. It’s very important to underline as in this study we demonstrate a marked decrease in ubiquitin and p53 immunoreactivity at 24 and 72 h. Our result emphasise the need to deeply the role of this receptor in UPS regulation as potential therapeutic target for cancer treatment.     

Electroactive chiral oligo- and polymer layers for electrochemical enantiorecognition

Different electrochemical response for the specular images of chiral probe molecules obtained in diastereomeric conditions provided by electrode functionalization with enantiopure electroactive oligo- or polymer layers.

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Masonry as structured continuum

A structured continuum model is formulated to describe the behaviour of block masonry modelled as distinct rigid body systems with elastic interfaces. A correspondence between the two motions is obtained by postulating a relationship between the displacement fields of the continuum and the discrete models. The constitutive functions for the dynamic actions of the continuum are derived by equating the power of the two models.A preliminary version was presented at AIMETA '92, congress held at Trento, Italy, on 28 September – 2 October 1992.