Transport in random quantum dot superlattices

We present a novel model to calculate single-electron states in random quantum dot superlattices made of wide-gap semiconductors. The source of disorder comes from the random arrangement of the quantum dots (configurational disorder) as well as spatial inhomogeneities of their shape (morphological disorder). Both types of disorder break translational symmetry and prevent the formation of minibands, as occurs in regimented arrays of quantum dots. The model correctly describes channel mixing and broadening of allowed energy bands due to elastic scattering by disorder

Study of the protective capacity of a β-cyclodextrin polymer with chlorogenic acid (coffee antioxidant)

This study focuses on coffee as a source of antioxidants, hence, protecting from the damage caused by free radicals; which has been demonstrated to have a protective action in numerous diseases. This capacity is attributed to its phenolic compounds among which chlorogenic acid stands out, together with caffeic acid. Besides, cyclodextrins are well known for their capacity of forming inclusion complexes where the host molecule is located in the interior cavity, allowing the transport and storage of it. My experimental project is focused on the synthesis and characterization of a protective polymeric system formed by β-cyclodextrin, which is then going to be loaded with chlorogenic acid. This inclusion complex as well as the β-cyclodextrin polymer and chlorogenic acid themselves, have been studied through preliminary studies of stability, using principally UV and FTIR spectroscopies as well as thermogravimetric calorimetry, which showed that the polymer prevents the acid from degrading through time, when maintained either at dark or in direct sunlight. The protective effect has been determined through scavenging capacity measurements analyzing the variation in the activity of chlorogenic acid as well as its change when the acid is introduced into β-cyclodextrin. For this, it has first been studied the change in absorbance using a mixture of 2,2-diphenil- 1-picrylhydrazyl (DPPH) and chlorogenic acid at different concentrations; leading to the already known fact that, at higher concentrations, the antioxidant capacity increases. Furthermore, the controlled release of the antioxidant from the cavities of the β- cyclodextrin in the polymeric matrices has been studied through Sotax Dissolution tests and applying mathematical models. This data leads to the conclusion that the CD-chlorogenic acid inclusion complex helps to maintain the integrity and scavenging activity of the bioactive compound especially when the chlorogenic acid is measured over time

Ocorrência de Anastrepha fraterculus (Diptera:Tephritidae) em butiazeiro (Butia odorata) na região de Pelotas, RS.

O objetivo do trabalho foi registrar a presença de dípteros da família Tephritidae em pomares na área experimental da Embrapa Clima Temperado, em Pelotas, RS

Entomofauna associated to different phenological stages on blueberry crop.

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The Effect of Slamming Impact on Out-of-Autoclave Cured Prepregs of GFRP Composite Panels for Hulls

This paper proposes a methodology that employs an experimental apparatus that reproduces, in pre-impregnated and cured out-of-autoclave Glass Fiber Reinforced Polymer (GFRP) panels, the phenomenon of slamming or impact on the bottom of a high-speed boat during planing. The pressure limits in the simulation are defined by employing a finite element model (FEM) that evaluates the forces applied by the cam that hits the panels in the apparatus via microdeformations obtained in the simulation. The methodology requires that various impact series be performed at different energies and that the evolution of the damage be followed via immersion ultrasound inspection to quantify how the material behaves, in addition to evaluating the delamination process via penetrating dyes using UV radiation. Slamming impacts were performed on the order of 105, and the micromechanisms of interlaminar and intralaminar damage propagation were observed with scanning electron microscopy (SEM). The results were analyzed by correlating them with pressure, deformation, impact energy, and applied cycles, in addition to conducting compression experiments after impact to relate the material damage with the residual strength of the impacted panels