Structural Characterization of Doped GaSb Single Crystals by X-ray Topography

We characterized GaSb single crystals containing different dopants (Al, Cd and Te), grown by the Czochralski method, by x-ray topography and high angular resolution x-ray diffraction. Lang topography revealed dislocations parallel and perpendicular to the crystal's surface. Double-crystal GaSb 333 x-ray topography shows dislocations and vertical stripes than can be associated with circular growth bands. We compared our high-angular resolution x-ray diffraction measurements (rocking curves) with the findings predicted by the dynamical theory of x-ray diffraction. These measurements show that our GaSb single crystals have a relative variation in the lattice parameter ({Delta}d/d) on the order of 10{sup -5}. This means that they can be used as electronic devices (detectors, for example) and as x-ray monochromators

Characterization of tin dioxide nanoparticles synthesized by oxidation

AbstractTin dioxide (SnO2) is a promising material with great potential for applications such as gas sensors and catalysts. Nanostructures of this oxide exhibit greater activation efficiency given their larger effective surface. The present study presents results of the synthesis and characterization of tin dioxide under different conditions via oxidation of solid tin with nitric oxide. SnO2powder was characterized primarily by X-ray diffraction and scanning electron microscopy, as well as complementary techniques such as energy-dispersive X-ray spectroscopy, dynamic light scattering and Fourier transform infrared spectroscopy. The results indicated that the established synthesis conditions were suitable for obtaining rutile tin dioxide nanoparticles with a tetragonal crystal structure

Double doping: a method to decrease dislocation densities in LEC InP crystals

In this paper we shall report on the characteristics of LEC InP double doped with Cd and Te. Unlike (Cd,S)-doped material, (Cd, Te)-doped InP is p-type, with low-carrier concentration. In the following, the results of structural and electrical analysis carried out on several LEC InP crystals co-doped with Cd and Te are presented. The role of multiple doping as a strategy for dislocation reduction will also be discussed

Novel tick glutathione transferase inhibitors as promising acaricidal compounds

Ticks are important ectoparasites with a worldwide distribution. The most commonly used method for tick control involves the use of acaricides. The main problem is that its indiscriminate use has led to the selection of resistant tick populations. Glutathione transferases (GSTs) are enzymes that play an important role in the detoxification of several types of compounds used in commercial tick control products. This work aims to find new bioactive molecules through in vitro assays with a panel of 160 molecules with putative inhibitory activity on the Rhipicephalus microplus GST enzyme (RmGST). Also, selected molecules were tested against GSTs from other tick species; Rhipicephalus decoloratus, Amblyomma variegatum, Rhipicephalus appendiculatus, and Haemaphysalis longicornis. The first screening on RmGST identified 30 compounds with the ability to modify the enzymatic activity of this enzyme. These compounds included different chemical families, like chalcones, diarylideneketones, flavone, thiazoles, thiourea, steroids, thiadiazines, indazoles, and hydrazine. The most potent compounds against RmGST belong to the diarylideneketones family with an inhibition concentration of 50% of activity (IC50) between 7-50 μM. Interestingly, one of the most potent compounds was also an inhibitor of the GST from other tick species. Experiments with R. microplus adults and larvae showed toxicity at 150 μM, suggesting a potential acaricidal effect of these molecules