Search results for "Dispersion"
showing 10 items of 1101 documents
Investigating self-assembly and metal nanoclusters in aqueous di-block copolymers solutions
2002
Self-assembling properties of di-block copolymers/ surfactant hybrids in aqueous solution can be exploited to obtain metal nanoparticles stable dispersion. Results will be presented here for polystyrene-block-poly(ethylene oxide) solutions. A SANS structural investigation has been performed over different molecular weights of both hydrophilic and hydrophobic block, by varying temperature and concentration of the copolymer. A SAXS characterization of micellar systems containing Pt nanoparticles is reported.
ChemInform Abstract: Palladium-Polypyrrole Nanocomposites Pd@PPy for Direct C-H Functionalization of Pyrroles and Imidazoles with Bromoarenes.
2016
Palladium–polypyrrole nanocomposites (Pd@PPy) with unique combination of high palladium dispersion (nanoparticle size 2.4 nm) and high palladium content (35 wt%) are efficient catalysts for the selective arylation of substituted pyrroles and imidazoles with either activated or deactivated aryl bromides. The performances of the recoverable supported palladium catalyst matches the best performances of homogeneous systems based on Pd(OAc)2 at 0.5–0.2 mol%, and largely overwhelm the classical Pd/C catalyst.
Inverse dispersion design in silicon waveguides
2014
We present a numerical tool to find the cross-section geometry of silicon-oninsulator waveguides that leads to a target dispersion profile. In < 10 iterations, we achieve geometries providing ultraflattened dispersion over 350 nm bandwidth.
Prevenire l’insuccesso scolastico nella scuola secondaria di primo grado: scuola e territorio dialogano
2017
Con il lavoro di co-progettazione per la promozione di una rete integrata tra soggetti pubblici e privati attraverso lo sviluppo di una metodologia di sistema, l’ideazione e realizzazione di strumenti di supporto, è stato offerto un contributo per il contrasto del fenomeno della dispersione scolastica e per la prevenzione del rischio di marginalità sociale negli adolescenti di Palermo. Il progetto ha coinvolto 172 studenti, 171 genitori e 29 docenti di tre scuole secondarie di primo grado, 10 operatori del terzo settore del territorio del Comune di Palermo. Si è partiti dal presupposto che per favorire la dimensione orientativa della scuola media fosse necessario incentivare il dialogo tra …
Restoration of a polymateric sculpture of the immaculate conception
2016
This study focuses on the intervention methodologies applied on a polymateric polychrome sculpture of the Immaculate Conception (18th century), located inside the chapel of the Oratorio dei Falegnami in Palermo. The peculiarity of this artefact is the employment of two different supports, upon which both the ground and paint layers are laid: a wooden one, carved and prepared, for the execution of the anatomical parts, and a textile one, sewn, pinned on and stiffened with glue, for the garments. The damage found was mainly attributed to: reaction of the artwork’s materials to the environment, lack of ordinary maintenance, and previous interventions. On the textile support, cleaning was hinde…
Il suolo come risorsa. Nuovi scenari nella Spagna post-crisi
2014
Se ‘tutela’ e ‘aggressione’ costituiscono i due estremi entro il quale trova diritto di cittadinanza il dibattitto teorico sul contenimento del consumo di suolo in Spagna, il caso di Valencia restituisce fisicamente gli esiti di questa tensione. Un territorio metropolitano dove il caos dell’edificazione e le aree di alto valore ecologico-ambientale convivono testimoniando le difficoltà e le contraddizioni del dibattito urbanistico che vive oggi la Spagna. Eppure, come vedremo, si tratta di dinamiche perfettamente comprensibili nel quadro dei processi urbani contemporanei e che, in maniera più o meno evidente, sono rintracciabili nella totalità dei paesi del sud europeo. Questo contributo vu…
Disease dispersion as a spatial interaction: The case of Flavescence Dorée
2020
International audience; Flavescence dorée is a serious and incurable vine disease transmitted by an insect vector. Focusing on its spatial diffusion and on its control with pesticides, this paper investigates the private strategies of wine producers and their socially optimal counterparts. The socially optimal regulation has to address two externalities regarding private treatment decisions: (a) the insufficient consideration of collective benefits from controlling the vector populations; (b) the failure to take into account environmental damage related to pesticide application. The probability of infection is estimated on French data from a spatial econometric specification. Three alternat…
Non-linear optical, electrochemical and spectroelectrochemical properties of amphiphilic inner salt porphyrinic systems
2016
Three zwitterionic meso-substituted A3B- and AB2C-porphyrins containing one sulfonato alkylpyridinium substituent and three or two alkoxy-substituted phenyl groups were synthesized in good yield and fully characterized as to their physicochemical properties by a variety of techniques. This new series of inner salt donor-acceptor meso-substituted porphyrin derivatives were prepared for possible application as amphiphilic probes for membrane insertion in the area of combined second-harmonic and two-photon fluorescence cellular microscopy. To this end, the linear and nonlinear optical properties of the compounds were characterized, together with their electrochemical and spectroelectrochemica…
A note on discrete sets
2009
We give several partial positive answers to a question of Juhasz and Szentmiklossy regarding the minimum number of discrete sets required to cover a compact space. We study the relationship between the size of discrete sets, free sequences and their closures with the cardinality of a Hausdorff space, improving known results in the literature.
Effective Hamiltonians in Nonrelativistic Quantum Electrodynamics
2021
In this paper, we consider some second-order effective Hamiltonians describing the interaction of the quantum electromagnetic field with atoms or molecules in the nonrelativistic limit. Our procedure is valid only for off-energy-shell processes, specifically virtual processes such as those relevant for ground-state energy shifts and dispersion van der Waals and Casimir-Polder interactions, while on-energy-shell processes are excluded. These effective Hamiltonians allow for a considerable simplification of the calculation of radiative energy shifts, dispersion, and Casimir-Polder interactions, including in the presence of boundary conditions. They can also provide clear physical insights int…