Clonagem e análise de variabilidade de Bean golden mosaic virus, no Estado de Goiás.

O Bean golden mosaic virus (BGMV) é o vírus causador do mosaico-dourado, responsável por prejuízos consideráveis em lavouras de feijão-comum. A variabilidade genética deste vírus é considerada baixa, e em geral existem poucas substituições nucleotídicas, de acordo com a localidade de origem dos isolados. Para analisar a variabilidade genética de geminivirus isolados do Estado de Goiás foram coletadas duas amostras de folhas de feijão-comum com sintomas típicos de infecção por BGMV, uma delas em Luziânia, GO, e outra em Santo Antônio de Goiás, GO. Foi realizada a extração de DNA e, em seguida, PCR com primers universais para geminivírus. Posteriormente, foi realizada, a partir do DNA total, uma reação de RCA para amplificação dos genomas virais

Laserlike emission from silica inverse opals infiltrated with rhodamine 6G

Monodisperse latex spheres were obtained by a surfactant free styrene polymerization method and used to obtain colloidal crystals by controlled centrifugation settling. Silica inverse opals were then prepared by using the colloidal crystals as templates and TEOS/ethanol solution. The inverse opals were infiltrated with Rhodamine 6G and laserlike emission was observed at 590 nm under 532 nm pump wavelength. The data show line narrowing of the dye fluorescence and a laser threshold of similar to 0.1 mJ/pulse. Local-field effects and light scattering due to structural defects are the main mechanisms contributing to generation of the laser-action observed. (c) 2005 Elsevier B.V. All rights reserved

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

COMPARATIVE ANALYSIS BETWEEN EXPERIMEN- TAL CHARACTERIZATION RESULTS AND NUMERI- CAL FDTD MODELING OF SELF-ASSEMBLED PHO- TONIC CRYSTALS

Abstract—This paper presents a comparative analysis between the experimental characterization and the numerical simulation results for a three-dimensional FCC photonic crystal (PhC) based on a self-assembly synthesis of monodispersive latex spheres. Specifically, experimental optical characterization, by means of reflectance measurements under variable angles over the lattice plane family [1, 1, 1], are compared to theoretical calculations based on the Finite Difference Time Domain (FDTD) method, in order to investigate the correlation between theoretical predictions and experimental data. The goal is to highlight the influence of crystal defects on the achieved performance. 1

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