Search results for "Dispersion."

Autosabotaggio e procrastinazione: strategie di prevenzione del sentire mafioso

2017

Nell’analisi della dispersione scolastica il fenomeno della procrastination è stato spesso sottovalutato. La nostra ricerca ha correlato i processi di selfhandicapping con quelli connessi all’abbandono del percorso di studio. La procrastination è stata studiata come processo di co-stante rinvio degli impegni scolastici e delle occasioni di recupero. Lo studio è stato condotto su di un gruppo di 956 studenti delle scuole superiori, distin-guendo due diverse aree: quella delle strategie di studio e di coping nella gestione delle prove scolastiche; quella delle relazioni sociali e delle priorità in esse. Queste variabili sono state correlate con il locus of control e con le strategie di self e…

Sports teams as complex adaptive systems: manipulating player numbers shapes behaviours during football small-sided games

2016

Small-sided and conditioned games (SSCGs) in sport have been modelled as complex adaptive systems. Research has shown that the relative space per player (RSP) formulated in SSCGs can impact on emergent tactical behaviours. In this study we adopted a systems orientation to analyse how different RSP values, obtained through manipulations of player numbers, influenced four measures of interpersonal coordination observed during performance in SSCGs. For this purpose we calculated positional data (GPS 15 Hz) from ten U-15 football players performing in three SSCGs varying in player numbers (3v3, 4v4 and 5v5). Key measures of SSCG system behaviours included values of (1) players’ dispersion, (2) …

Oil solubilization in copolymer and copolymer covered laponite aqueous dispersion

2007

Chasing Weak Forces: Hierarchically Assembled Helicates as a Probe for the Evaluation of the Energetics of Weak Interactions.

2017

London dispersion forces are the weakest interactions between molecules. Because of this, their influence on chemical processes is often low, but can definitely not be ignored, and even becomes important in cases of molecules with large contact surfaces. Hierarchically assembled dinuclear titanium(IV) helicates represent a rare example in which the direct observation of London dispersion forces is possible in solution even in the presence of strong cohesive solvent effects. Hereby, the dispersion forces do not unlimitedly support the formation of the dimeric complexes. Although they have some favorable enthalpic contribution to the dimerization of the monomeric complex units, large flexible…

Development of microfluidics for sorting of carbon nanotubes

2018

Sorting of carbon nanotubes by their chirality is the current bottleneck in the way to their broad employment based on their exceptional electronic and optical properties. Despite the extensive effort, there is no known method, which would result in really pure chirality ensembles. Previously reported sorting protocols result in enrichment rather than in sorting, alter electronic structure, and suffer from low yield. This is mostly due to the statistical approach, where the nanotubes with mixed chiralities are treated as a set. In this thesis, we propose a new sorting technique based on nanotube-by-nanotube compartmelization, characterization, and sorting in a continuously running droplet-b…

Structure and dielectric breakdown strength of nano calcium carbonate/polypropylene composites

2013

Nanodielectrics, a 21st-century phenomena, is envisioned to be the answer for material challenges in progressive high-voltage technology. It is well known that the proper dispersion of nanoparticles plays a key role in improving the dielectric properties of a material, but to understand where changes in the properties of a material originate, it is also essential to reveal the multiscale structure of the material. In this study, the dielectric permittivity, breakdown strength, and structure of nano calcium carbonate (nano-CaCO3)/polypropylene composites with 1.8-8.1 wt % doping were characterized systematically. The combined results from transmission electron microscopy, Raman microscopy, a…

A one-pot method to enhance dissolution rate of low solubility drug molecules using dispersion polymerization in supercritical carbon dioxide

2009

Competition of electron-phonon mediated superconductivity and Stoner magnetism on a flat band

2018

The effective attractive interaction between electrons, mediated by electron-phonon coupling, is a well-established mechanism of conventional superconductivity. In metals exhibiting a Fermi surface, the critical temperature of superconductivity is exponentially smaller than the characteristic phonon energy. Therefore, such superconductors are found only at temperatures below a few kelvin. Systems with flat energy bands have been suggested to cure the problem and provide a route to room-temperature superconductivity, but previous studies are limited to only BCS models with an effective attractive interaction. Here we generalize Eliashberg's theory of strong-coupling superconductivity to syst…

Engineered surface waves in hyperbolic metamaterials

2013

We analyzed surface-wave propagation that takes place at the boundary between a semi-infinite dielectric and a multilayered metamaterial, the latter with indefinite permittivity and cut normally to the layers. Known hyperbolization of the dispersion curve is discussed within distinct spectral regimes, including the role of the surrounding material. Hybridization of surface waves enable tighter confinement near the interface in comparison with pure-TM surface-plasmon polaritons. We demonstrate that the effective-medium approach deviates severely in practical implementations. By using the finite-element method, we predict the existence of long-range oblique surface waves. This research was fu…

Génération de similaritons optiques à 1550 nm par amplification Raman dans une fibre NZ-DSF

2004

Nous presentons la premiere observation experimentale de similaritons optiques generes par amplification Raman a 1550 nm dans une fibre a dispersion decalee. Une caracterisation FROG des impulsions indique un profil d'intensite parabolique et un chirp lineaire conformes aux predictions theoriques.