Collodi e la matematica. L’Abbaco di Giannettino e l’aritmetica per le scuole elementari italiane a cavallo tra XIX e XX secolo

The authors present a first study about some mathematics texts for children written by Carlo Lorenzini (Collodi) between 1884 and 1889. In addition to his most famous literary works, Pinocchio’s father, in fact, wrote a series of didactic booklets for boys and girls of the lower cycle of elementary schools, which were published in the «Collana Scolastica» of the Paggi publisher in Florence. These booklets consist of the so-called Giannettini series, centered on the character of Giannettino, as well as two Libro di Lezioni respectively for the Second and the Third elementary class (1889). Here the lesser known L’Abbaco di Giannettino per le scuole elementare (1884) will be analysed and compared with the Lezioni of 1889, with respect to mathematics content, literary style and teaching approach used by Collodi

Rare earth doped synthetic opals and inverse opals

Monodisperse spheres of silica and latex were obtained by a surfactant free styrene polimerization and the Stober method respectively. Controlling settling either by centrifugation or by dip-coating colloidal crystals could be obtained. Silica inverse opals were prepared by using the latex colloidal crystals as templates and TEOS/ethanol solution. Eu3+ containing silica spheres were obtained dispersing silica spheres in Eu(NO3)(3) isopropanol solutions. Emission spectra suggest the formation of an amorphous Eu3+ containing phase well adhered at the spheres surface. The utilization of solutions of trifluoroacetates salts of Pb2+ and Eu3+ was observed to destroy the silica spherical pattern when samples are treated at 1000degreesC. In that case nanocrystals of PbF2 and amorphous silica were obtained after heat treatment.UNESP, Inst Chem, BR-14801970 Araraquara, SP, BrazilUNESP, Inst Chem, BR-14801970 Araraquara, SP, Brazi

Effects of self-assembly process of latex spheres on the final topology of macroporous silica

This paper surveys the topology of macroporous silica prepared using latex templates covering the submicrometric range (0.1-0.7 mu m). The behavior of latex spheres in aqueous dispersion has been analyzed by dynamic light scattering (DLS) measurement indicating the most appropriate conditions to form well-defined cubic arrays. The optical behavior of latex spheres has been analyzed by transmittance and reflectance measurements in order to determine their diameter and filling factor when they were assembled in bidimensional arrays. Macroscopic templates have been obtained by a centrifugation process and their crystalline ordering has been confirmed by porosimetry and scanning electron microscopy. These self-assembled structures have been used to produce macroporous silica, whose final topology depends on the pore size distribution of the original template. It has been seen that latex spheres are ordered in a predominant fcc arrangement with slipping of tetragonal pores due to the action of attractive electrostatic interactions. The main effect is to change the spherical shape of voids in macroporous silica into a hexagonal configuration with possible applications to fabricate photonic devices with novel optical properties. (c) 2005 Elsevier B.V. All rights reserved