1,721,023 research outputs found
La particella alla fine dell'universo. La caccia al bosone di Higgs e le nuove frontiere della fisica
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Role of hydrostatic paradoxes towards the formation of the scientific thought of students at academic level
Full text linkThe importance of fluid mechanics is often underrated. Besides studying the mechanisms governing static and dynamic fluids, this discipline could have a great role in the understanding of many principles, topics and concepts of general mechanics. When approached in a proper way, fluid mechanics provides numerous 'case studies' apt to clarify the physical content of several mechanical laws. Unfortunately, fluid mechanics, in physics classes, is generally viewed as a 'lower branch' of mechanics. Its rules and laws too often are regarded as too particular, or even as special cases, to deserve the same attention paid to other arguments. The help that fluid mechanics could return in the learning process can be proved by some easy considerations. In this frame, the so-called hydrostatic paradoxes could provide a tremendous contribution to the learning processes
Tuning the surface morphology of self-assembled graphene-like thin films through pH variation
No full textGraphene-like (GL) layers were prepared through a two steps oxidation/reduction method starting from a high surface carbon black, and pH of the GL layers in water suspension was varied. The effect of pH of such suspension on the morphology of self-assembled GL films has been studied. Zeta potentials of the water suspensions were measured to estimate the stability of the suspension at several pH values and to select the samples for deeper investigation by atomic force microscopy (AFM). AFM measurements on four different samples are then described and discussed. The reported results show how the surface roughness and morphology are affected by the pH in the preparation process: in particular, the lowest pH sample exhibits a granular surface, while at higher pH more regular morphologies are produced, with interesting observations as concerns the thickness of some surface features. The observations are interpreted in terms of the forces acting in water suspension and of the role of hydrophobic or hydrophilic behaviors. The results demonstrate the possibility to tune the surface properties of GL films by simply acting on the pH of the suspension during the fabrication, and help to understand the microscopic physical mechanisms involved in the film assembly
A teaser made simple: a didactic measurement of the spectral answer of a human-eye-calibrated lux meter
No full textA simple didactic experiment has been designed and realized, in order to illustrate to undergraduate students in scientific faculties some basic concepts lying behind the fundamentals of geometrical optics. The spectral response of a human-eye-calibrated lux meter was measured using a very trivial experimental arrangement. The white light of a halogen lamp was decomposed into its spectral components through a diffraction grating, so that collecting the radiation at different dispersion angles allowed one to measure the intensity as a function of wavelength. The experiment can be used to effectively illustrate the concepts of spectral distribution, the radiometry versus photometry conversion and photopic response, and the famous historical experience by Herschel on the 'temperature of colours'
Synthesis and characterization of conductive copper-based metal-organic framework/graphene-like composites
Full text linkMetal-organic framework (MOP) incorporating conductive graphene-like layers were synthesized and characterized. The selected MOF, HKUST-1, combines high surface area, water stability, simple preparation and low costs. Graphene-like layers incorporated into the MOF structure were obtained by a two-step oxidation/reduction wet treatment of a high surface carbon black. MOF composites were produced at different carbonaceous layers content. It was shown, through a wide characterization of the samples, that the composites preserve the main features of the parent MOF, additional exhibiting a tunable electrical conductivity
Evolution of the charge density wave state in CuxTiSe2
No full textWe present scanning tunneling microscopy and spectroscopy measurements of the charge-density wave state in 1T-TiSe2, Cu0.05TiSe2, and Cu0.06TiSe2 single crystals. Topography images at 4.2 K reveal that the charge density waves are present in all samples studied, although the amplitude of the charge modulation decreases with the Cu doping. Moreover, the chiral phase of the charge density wave is preserved also in Cu-doped samples. Tunneling spectroscopy shows that there is only a partial gap in the pure compound, with bands crossing the Fermi surface. In the Cu-doped samples, the system becomes more metallic due to the increase of the chemical potential
Graphene-Like Layers from Unconventional Carbon Sources: New Perspectives on Hybrid Materials and π-system Synergisms
Full text linkWe developed a new approach for producing graphene-like (GL) materials through a two-steps oxidation/reduction method starting from a nanostructured (high surface) carbon black, a versatile carbonaceous material prone to be structurally and chemically modified in quite mild wet conditions. Atomic Force Microscopy and zetapotential measurements allowed to model the assembling mechanisms and the roleof hydrophobic interactions, demonstrating the possibility to easily tune the surface morphology. GL materials have been then employed in a large variety of hybrid materials for innovative applications, and characterized by chemical, electrical, structural and spectroscopic techniques. With Metal-Organic Frameworks, GL produced conducting composites with electrical conductivity tunable by changing the concentration of the parent materials; Eumelanin/GL and TiO2-nanoparticles/GL were also studied for photocatalysis and biosensors applications
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