Wide-angle filters based on nanoresonators for the visible spectrum.

We present a design for a highly efficient and omnidirectional color-selective filter for the visible spectrum, based on a Fabry-Perot metal-dielectric-metal nanoresonator. The filter can have the same color transmitted in a range of incident angles from 0° up to 60° for TM polarization. The dielectrics used for each color filter are carefully chosen so that the angle-insensitive resonance conditions are satisfied while transmission values from 44.3% to 78.36% are achieved. We calculated the dielectric thickness for each filter and analyzed the optimal Ag thickness for maximum transmission. The proposed filters have a simple multilayer structure and do not require complex lithographic fabrication processes.

Programmable nanophotonic planar resonator filter-absorber based on phase-change InSbTe.

Reconfigurable plasmonic-photonic electromagnetic devices have been incessantly investigated for their great ability to optically modulate through external stimuli to meet today's emerging needs, with chalcogenide phase-change materials being promising candidates due to their remarkably unique electrical and optics, enabling new perspectives in recent photonic applications. In this work, we propose a reconfigurable resonator using planar layers of stacked ultrathin films based on Metal-dielectric-PCM, which we designed and analyzed numerically by the Finite Element Method (FEM). The structure is based on thin films of Gold (Au), aluminum oxide (Al2O3), and PCM (In3SbTe2) used as substrate. The modulation between the PCM phases (amorphous and crystalline) allows the alternation from the filter to the absorber structure in the infrared (IR) spectrum (1000-2500 nm), with an efficiency greater than 70% in both cases. The influence of the thickness of the material is also analyzed to verify tolerances for manufacturing errors and dynamically control the efficiency of transmittance and absorptance peaks. The physical mechanisms of field coupling and transmitted/absorbed power density are investigated. We also analyzed the effects on polarization angles for Transversal Electric (TE) and Transversal Magnetic (TM) polarized waves for both cases.

[Utility of gamma rays in prophylaxis of transmissible malaria by blood transfusion]. / Estudo sobre a eventual utilidade de raios gama na profilaxia da malária transmissível por transfusão de sangue.

This study was carried out to evaluate the fortuitons advantage of using gamma irradiation in the prophylaxis of transmissible malaria by blood transfusion, with mice as the experimental model. In the first step, when the infected blood with Plasmodium berghei was submitted to 2,500 rad and 5,000 rad, with or without metronidazol, there was no success, because the animals presented parasitaemia and died after inoculation of irradiated blood. However, there was partial success in the second step, when the infected blood received 10,000 and 15,000 rad, and was inoculated in mice, which showed infection, and presented a survival rate of 20% and 40%, respectively, with later negativation of blood infected by P. berghei.